Track 1: 2024 Nickel-Cobalt-Copper Agenda
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Monday 27 May
8:00 am Conference Registration & Arrival Tea
9:00 Conference Chairperson’s Opening Remarks
9:10 Sponsor’s Welcome
9:15 KEYNOTE PRESENTATION: Recent Growth of Nickel Laterite Processing in Indonesia
Taufiq Hidayat, Researcher, Metallurgy Engineering Research Group, Institut Teknologi Bandung, Indonesia
Indonesia is one of the countries with significant nickel reserves contributing to approximately 20% of the total world nickel reserves. In 2022, Indonesia nickel mining production reached almost half of the total world nickel mining production. Nickel in Indonesia is predominantly found as laterite deposit with layers having different characteristics. The layer under the topsoil contains limonite ore with relatively low nickel and low MgO contents, while the layer located deeper but above the bedrock contains saprolite ore with relatively high nickel and high MgO contents. The Indonesian government has introduced a set of strategic regulations aimed at harnessing its nickel resources and strengthening its domestic industrial capacities. One of the prominent regulations is regarding the nickel ore export ban that was implemented to encourage domestic nickel processing. The export ban on ore has been a catalyst for the recent surge in nickel laterite processing in Indonesia. The law shifted Indonesia’s role from initially being one of the major exporters of nickel ore to the leading exporter of nickel containing intermediate and semi-finished products. The High-Pressure Acid Leaching (HPAL) is implemented for processing the limonite ore, while the Rotary Kiln Electric Furnace (RKEF) is dominantly applied for processing the saprolite ore. The development of HPAL and RKEF plants in Indonesia will be presented. In addition, the possible directions or strategies of the Indonesian nickel industry will be discussed.
9:55 Nickel Laterites—Grade Definition and Process Optimisation by Mineralogical Monitoring Using X-Ray Diffraction XRD
Uwe König, Global Mining Segment Manager, Malvern Panalytical, The Netherlands
Nickel laterite production is on the rise, surpassing conventional sulfide deposits, to ensure global supply in the future. Nickel laterite ore is used to produce nickel metal, predominantly to manufacture stainless steel as well as nickel sulfate, a key ingredient in the batteries that drive electric vehicles. The efficiency of mining and processing nickel laterites is defined by their mineralogical composition. Typical profiles of nickel laterites are divided into a saprolite and a laterite horizon. Nickel is mainly concentrated and hosted in a variety of secondary oxides, hydrous Mg silicates and clay minerals like smectite or lizardite in the saprolite horizon, whereas the laterite horizon can host cobalt that can be extracted as a side product. A case study from both saprolite and laterite horizons was performed using X-ray diffraction (XRD) in combination with statistical methods such as cluster analysis. Besides the identification of the different mineral phases, the quantitative composition of the samples was also determined with the Rietveld method. Data clustering of the samples was tested and allows a fast and easy separation of the different lithologies and ore grades. Mineralogy also plays a key role during further processing of nickel laterites to nickel metal. XRD was used to monitor the mineralogy of calcine, matte, and slag. The value of mineralogical monitoring for grade definition, ore sorting, and processing will be explained in the presentation.
10:25 The Atlas Materials Process for Low-Carbon Nickel
David Dreisinger, Co-Founder & President, Atlas Materials, Canada
Atlas Materials is a climate technology startup with the objective of producing low-carbon materials and contributing significantly to atmospheric decarbonisation. The Atlas Materials Process treats nickel laterite ore using hydrochloric acid leaching to produce a silica residue for addition to cement-making, a mixed hydroxide product containing nickel and cobalt for battery material processing, a small amount of manganese dioxide and magnesium hydroxide for the chemical market, and, in the longer term, for carbon sequestration. Natural olivine mineral and sodium hydroxide are used to neutralise and precipitate the various products. Hydrochloric acid and sodium hydroxide are regenerated using the chlor-alkali process. Atlas Materials has MOUs in place with two mining groups in New Caledonia (Société Minière Georges Montagnat (SMGM) and Société des Mines de la Tontouta (SMT)) for the supply of nickel saprolite ore. This ore will be processed in North America to create a domestic supply of nickel and cobalt for electrification of the transport sector while contributing to decarbonisation of cement-making and supply of the magnesium chemicals market. The results of the Atlas Materials Demonstration Pilot Plant program conducted at SGS Canada (Lakefield, Ontario) will be presented and discussed. The program has been conducted in separate campaigns around (1) saprolite milling, (2) hydrochloric acid leaching and olivine neutralisation for iron, aluminum, and chromium removal, (3) two-stage mixed hydroxide recovery, and, (4) manganese removal and magnesium hydroxide precipitation. Finally, the entire process has been operated in continuous fashion over an extended period to supply engineering data for the first commercial facility, products for commercial evaluation, and all necessary process environmental testing to facilitate permitting.
10:55 Morning Tea in the Exhibit Hall 
11:25 Sulfuric Acid Plant Integration in Nickel Hydrometallurgical Facilities
Matthew King, Manager, Business Development, Worley Chemetics, Australia
Nearly all base metals hydrometallurgical processes require sulfuric acid. This acid is often produced onsite in one or more conventional double contact double absorption (DCDA) type sulfuric acid plants. Onsite production has the key benefit of providing steam and electricity as co-products. This paper provides an overview of sulfuric acid plants used at nickel-leaching operations and insight into the challenges faced when balancing acid, steam, and electricity demand — especially during transient and turndown operation. CORE-SO2 technology is presented which has been tailored to specifically meet the industry’s need for lower capital cost, decreased tail gas emissions (without effluent generation), and maximised energy recovery, along with reliable turndown capability and zero CO2 emissions. CORE-SO2 plants can produce from 100 t/d up to 13,000 t/d of acid in a single train.
11:55 HPAL Autoclave Performance: A Comprehensive Design Exploration
Wolfgang Keller, Vice President Research & Development, EKATO, Germany
The extraction of nickel from lateritic ore bodies in horizontal HPAL autoclaves has evolved into a well-established and standard process. While the geometric design of these autoclaves has remained unchanged since the second generation in the 1990s, their size has substantially increased, with volumes doubling. From a process point of view the crucial role of effective mixing in the multiple compartments of HPAL autoclaves persists. This paper explores the intricate relationship between autoclave geometry and agitator design in standard setups, utilising cold flow test results obtained from a 400-liter model autoclave. The findings highlight the continued importance of optimising mixing processes within autoclaves—and provide insights into potential vessel design variations to optimise both Capex and Opex costs.
12:25 pm Autoclave Overpressure: The Hidden Variable
Rob Mock, Director of Research & Development, Nova Hydromet, Canada
Autoclave systems have traditionally been plagued by multiple issues, some of which receive more attention than others. The authors’ approach to pressure hydrometallurgy problem-solving uses first principles to look beyond common practice to mathematics- and physics-based solutions which often run counter to engineering intuition. Perplexing but common autoclave system issues can include autoclave letdown throughput limitations, broken letdown valve trim, excessive letdown circuit erosion, improper sizing, reaction kinetics modelling miscalculations, and harmonic autoclave level control oscillations. These issues all have several things in common: they result in costly and often unnoticed losses; resolution to obvious issues usually happens very slowly; they are significantly interrelated, sometimes at more than one level; and the interrelated sciences are generally not well understood. Overpressure in the autoclave and its discharge line is related to all these issues, as it affects the root causes of each. Several issues can be simultaneously addressed using the skilled application of multiple interdependent sets of first principle-based equations. A solid understanding of the related sciences and the added benefit of long industry experience help create solutions specific to each site. Autoclave overpressure provides the classic example of the absence of (or indifference to) complex but essential knowledge that leads to solutions and improvement. As a function of total autoclave pressure and discharge fluid temperature, overpressure can be understood as the partial pressure of non-condensable gases in the autoclave vapor space. Despite its dominant and extensive effects, it is not directly measured and rarely indirectly derived. Without receiving much attention autoclave overpressure has effectively remained a hidden variable for decades. Accordingly, overpressure fluctuates significantly in most autoclaves. That high variability is detrimental in multiple ways. Consequently, many autoclave sites incur millions of dollars in silent production losses each year. Throughput limitations of this type are often built into production baselines and are thus completely unknown to plant personnel. Strategies for better comprehending and managing autoclave overpressure leading to performance enhancement will also be presented, along with some descriptive mathematics essential to the relevant sciences.
12:55 Sponsor’s Welcome 
12:55 Networking Luncheon (Sponsored by Caldera Engineering)
1:50 Chairperson’s Afternoon Remarks
1:55 Long-Term Experiences and New Developments in Autoclave Linings for High-Pressure Leaching and Pressure Oxidation Processes
Daniel Kessler, DSB Säurebau, Germany
Common processes to extract metals from refractory or laterite ores rely on high pressure applications in autoclaves, e.g., High-Pressure Acid Leaching (HPAL) to extract nickel and cobalt or Pressure Oxidation (POX) in cases of copper, gold, zinc, etc. In both processes, ore is mined, crushed, and a slurry is created by addition of water or acid. This slurry is treated at elevated temperature and pressure (e.g., T>200°C, P>30 bar) in an autoclave. To return the slurry to atmospheric conditions, an array of flash vessels is used. Via decantation and selective precipitation, the desired metal, metal oxide, or metal salt can be accumulated and purified. As each step requires a specific corrosion protection lining, different lining setups are used in autoclaves, flash vessels, etc. Especially for high pressure applications in autoclaves and flash vessels, combined linings of membranes, bricks, and inserts of PTFE, titanium or Inconel are used. Looking at various ore processing plants around the world, different kinds of membranes are combined with different types of brick linings aiming for a long-lasting and efficient corrosion protection. Membranes protect the steel vessels against chemical attack. Widely used in pressure vessels are lead membranes, glass fiber reinforced coatings, or rubber linings. Also, explosion-plated titanium or welded-on Inconel is partially used. The main task of the additional brick lining is to protect the membrane against abrasion or mechanical impact. Acid resistant ceramic bricks, carbon bricks, graphene bricks, or different specialties are widely used. Depending on the local load (e.g., liquid phase, gas phase, transition zone) different types of mortars are used to install the brick lining. During the presentation, we will look back on decades of experience with different lining combinations and show pros and cons in application, operation, maintenance, repair, and relining.
2:25 DetaPipe Changing Reactive Metal Pipe Systems for HPAL and POX Operations
Edgar Vidal, Vice President Marketing & Business Development, NobelClad, USA
Availability and supply chain concerns around titanium are always in the minds of designers and end users of High-Pressure Acid Leaching (HPAL) and Pressure Oxidation (POX) circuits. Because of the extreme conditions of temperature, pressure, and acidity, titanium alloys are often selected for components of these circuits, such as the autoclave itself, valves, pipe straights, and elbows. Because of the relatively thick walls needed for these pipes and elbows, the cost of these components can become an economic concern for the project. Additionally, handling, fixturing, and repairing a solid titanium pipe adds technical challenges, particularly in remote operations. NobelClad has developed a proprietary cylindrical cladding process to produce a titanium-, zirconium-, or tantalum-clad surface inside carbon or stainless-steel pipes—called DetaPipe. In combination with explosion-cladded flanges (DetaClad), these pipe spools and elbows utilise significantly less titanium alloys, where these alloys become just a corrosion barrier and not part of the pressure boundary. Because of the unique characteristics of the cladding process, many different titanium alloys can be used, including those that have increased corrosion, erosion, and ignition resistance, which tend to be significantly more expensive when compared to pure titanium. Examples of combinations produced, along with mechanical, thermal, and fatigue characterisations performed, are presented.
2:55 Implementation of Selective Oxidation at Lihir Gold Operations Papua New Guinea
John O’Callaghan, Consultant, Australia
On 10 December 2014, Lihir Gold Operations changed from full oxidation of gold containing auriferous sulfides to selective oxidation. Most of the gold at Lihir is contained in high-arsenic pyrite or arsenian pyrite and this pyrite is the target for preferential or selective oxidation. The installed and fixed cryogenic oxygen supply capacity is used to oxidise arsenian pyrite in preference to low-grade “barren” pyrite thereby maximising gold production. This paper briefly describes the history of the Lihir process plant and the implementation of the selective oxidation process using the new operating strategy. Specific lime, cyanide, and other reagent usage in the downstream Carbon-in-Leach gold recovery circuit has remained largely unchanged. Other deposits of similar mineralogy may benefit from a selective oxidation approach.
3:25 Afternoon Tea in the Exhibit Hall
3:55 Proposed Bacterial Heap Leaching of Ore Sorter Products at Anax Metals’ Innovative Whim Creek Project
Tony Parry, Senior Consultant, Nexus Bonum, Australia
Anax Metals Limited (“Anax”) is planning to recommence mining and processing operations at the historic Whim Creek mining center located 120 km southwest of Port Hedland, with a vision to developing a strategic polymetallic ore processing hub in the Pilbara. The Whim Creek Project is a joint venture between Anax (80%) and Develop Global Limited (20%). Oxide ore was mined from Whim Creek and Mons Cupri volcanic-hosted massive sulfide (VMS) deposits by Straits Resources Limited (now Aeris Resources Ltd.) in the mid-2000s and processed through a heap leach and SX/EW plant to produce around 15,000 tpa of copper cathode. Much of the heap leach infrastructure remains. Anax acquired its interest in the Project in late 2020. In April 2023, a Definitive Feasibility Study (“DFS”) to produce 10,000 to 12,000t of copper equivalent metal per year from sulfide ore was completed. The Whim Creek DFS flowsheet to treat copper-zinc-lead sulfide ores with significant precious metals credits is innovative, incorporating two stages of sensor-based ore sorting prior to further metallurgical processing. The first-stage primary ore sorters will upgrade the ROM ore into higher-grade pre-concentrates which will then be processed in a new purpose-built copper-zinc-lead concentrator to produce saleable sulfide concentrates. The rejects from the primary ore sorters will be further treated in a secondary ore sorting circuit to produce a ‘middlings’ pre-concentrate and barren rejects that potentially can be used as commercial aggregates. It is intended to treat the middlings pre-concentrates in the existing heap leach circuit (after refurbishment) to produce copper metal (from SX-EW) and a separate zinc sulphate byproduct stream. The Whim Creek copper mineralisation is primarily chalcopyrite and therefore Anax believes that the proposed heap leach operation will need to incorporate bacterial leaching in order to achieve satisfactory copper recoveries. This paper describes the proposed innovative pre-concentration circuit, the bacterial heap leach test work undertaken by Anax using ore sorter middlings pre-concentrates generated in ore sorting test work, as well as discussing the refurbishment requirements and circuit modifications likely to be required for a restart of the existing heap leach and SX-EW infrastructure. The bacterial leaching test work was conducted using native bacterial cultures extracted from remnant fluids in the Whim Creek pits. Column leaching test work has produced excellent results, as announced by Anax in June 2023. The tests confirmed that bacterial column leaching test work delivered 79-80% copper extraction and over 90 zinc extraction from the ore sorter middlings. Bioleaching test work is ongoing with larger column tests underway and optimisation of conditions to further improve both copper and zinc extraction. Meanwhile, Anax has progressed studies into the refurbishment of the heap leach and SX-EW infrastructure, the key elements of which are also described in this paper.
4:25 Solution Rate Techniques for Copper Ore Column Leaching Testing
Fernando Zeballos, Director of Metallurgical Projects, Compañía de Minas Buenaventura, Peru
To run a laboratory column leaching testwork of a copper ore, the most recommendable method would be to use columns with similar or equal height of operating or designed heap lift. The main reason why it is always not possible is because full height columns demand more ore and during the project study stages it could be a restriction because the representative samples come from drill cores mainly, which are used for other project purposes, also. On the other hand, the most common solution rate used for columns leaching testing, independently of column height, is a single rate equal to solution rate considered for industrial heap operation. When applied a full and unique solution rate for all columns size without considering the mass of ore loaded in each column, final kinetic results will be different, hence, will need to use equivalence factors to standardize and analyse the testwork results, and finally use the data for heap design. With the necessity to start a variability column leaching testwork using samples by mine bench height to support the FS of Trapiche project, in Buenaventura was run a laboratory test with three different column heights (1m, 3m, and 6m), using the same composite crushed and agglomerated copper ore and the same leaching conditions, but equivalent irrigation solution rates. Solution rates were based on full-scale eight meters lift height (around 5 L/m2-h) and reduced proportionally in function of ore mass loaded to each column. Ore mass is proportional to each column height. All test leaching columns have the same diameter, six inches. Considering a leaching cycle of 184 days, an average copper recovery of 72% and similar kinetic curves for all three leaching columns was obtained. This indicates that the application of reduced solution rate or equivalent solution rate technique could be applied to short leaching columns and the copper recovery behavior will be the same as if full-sized columns had been used. This technique will be utilised in the Trapiche project variability metallurgical leaching campaign (120 columns) with one meter column height; it is aligned with the small availability of core drilling samples. Variability in metallurgical testwork results will be used to develop the copper recovery and acid consumption geo-metallurgical project models.
4:55 Modelling Copper Leaching in Heap Systems Considering Competing Reaction Mechanisms and Coupled Dissolution with Reprecipitation (Cdr) Processes
Eric O. Ansah, Researcher, University of Melbourne, Australia
Chalcopyrite, an abundant source of copper, is noted to undergo slow dissolution under ambient conditions due to the formation of secondary minerals at the chalcopyrite surface also referred to as surface passivation. Although the passivation mechanism has been extensively studied, present models do not adequately account for it. Hence, passivation limiting copper recovery from chalcopyrite was explored and demonstrated by implementing a surface passivate model (SPM) in this reaction pathway modelling (RPM) study. In addition, the role of different gangue minerals and different chalcopyrite dissolution mechanisms were assessed, and the state of saturation was determined for various minerals to constrain limiting conditions for copper recovery. RPM with different rate laws describing proton-promoted, ferric-iron promoted, and combined ferric-iron-proton-promoted chalcopyrite dissolution in the presence of gangue minerals in chloride system were used. The reaction mechanism that facilitated the fastest dissolving of chalcopyrite and the largest mobilisation of copper was that induced by ferric iron. Nonetheless, the production of iron-hydroxy sulphates (like jarosite), iron oxide (hematite), and various gangue minerals inhibited the mobilisation of copper, underscoring the significance of precisely depicting primary and secondary reactions, their co-location, and their reaction behavior. The SPM was able to simulate jarosite surface covering of the chalcopyrite surface, reducing the reactive surface area, and hindering chalcopyrite dissolving in the process. On the other hand, because covellite was consistently undersaturated in trial models, the SPM was unable to simulate the incongruent dissolution of chalcopyrite, resulting in a copper sulfide layer deficient in iron. Additionally, the dissolution of chalcopyrite may be positively impacted by the presence of gangue minerals like hematite and gypsum, but negatively impacted by the presence of silicates like feldspar and muscovite. The results of this investigation are significant because they offer fresh perspectives on the simultaneous processes governing copper recovery in heaps and the most effective modelling techniques for these reactions.
5:25 Integration of Hydrometallurgy Process and Mineral Carbonation Technology
Yasunori Nozoe, Engineering Manager, JGC Corporation, Japan
The metal smelting and refining field is facing a dilemma to satisfy the social demand to reduce carbon dioxide (CO2) emissions while maintaining supply chains by fulfilling the increasing demand for metal resources, such as for batteries and magnetics, as high-grade mineral resources continue to become depleted. Regardless of the market requirements, the need to respond to such social demands cannot be ignored. Carbon dioxide capture, usage, and storage (CCUS) is one of the measures to reduce CO2 emissions, and JGC has been developing its own technology by focusing on a CCUS using mineral carbonation (CO2 mineralization). CO2 mineralization is a technology that reacts with and solidifies CO2 by forming chemical compounds with calcium and magnesium (Ca and Mg) sources such as basic rocks. As to the methodology of the reaction, a high-pressure method is commonly known, but JGC has been focusing instead on a method at atmospheric pressure. In the beginning, a CO2 mineralization method using serpentine had been studied, however, a simplified economic study showed a negative result in terms of profitability due to its limited income based on CO2 credits and magnesium carbonate sales revenue alone. Conversely, in the field of nickel hydrometallurgy, sulfuric acid leaching methods, such as high-pressure acid leach (HPAL), are attracting attention in recent years because the process produces nickel sulphate and mixed hydroxide precipitate (MHP) as the precursor materials of lithium ion batteries (LiB) from nickel laterite ores. However, high-Mg ores have no affinity to the acid leaching process, as its Mg consumes the acid reagent and lowers the feasibility, therefore, high-Mg ores have not been actively processed but probably stockpiled at mine sites. JGC has developed a method to integrate the sulfuric acid leaching process and CO2 mineralization, which converts high-Mg ore into a nickel resource and reduces CO2 emissions at the same time. This paper introduces the abovementioned JGC’s methodology and results of laboratory tests using actual nickel laterite ore samples and describes the improvement in a simplified economic study.
5:55 Sponsor’s Welcome 
5:55 Welcome Reception in Exhibit Hall (Sponsored by Syensqo)
7:55 Close of Day
Tuesday 28 May
8:00 am Registration & Arrival Tea
9:00 Chairperson’s Opening Remarks
9:05 Breaking Free of the New Mine Development Catch-22
Matt Schneider, CTO, Idoba, Australia
Developing a new mine is one of the toughest endeavors out there, yet our renewable future requires a lot of minerals from new mines sympathetic to the sustainability cause (low-impact, efficient, safe). Overlay the industry’s historically low success rate and the rising cost of capital, and you have an extremely challenging environment for developing new mines. Consequently, many projects get stuck in the “Study Phase Catch-22” (can’t advance beyond scoping phase without investment, can’t get investment without advancing beyond scoping phase). Decisions informed by directed experience and systems thinking is one of the keys to breaking out of this cycle, however for many proponents this is their first mine development project therefore creating another catch-22. To formulate an assistance tool, we started by imagining being able to see the components of a proposed value chain laid out visually to show the key linkages, and then being able to flex elements of the system as a function of time to immediately see the financial and process implications of doing so. Inspired by AusIMM’s Technical Economic Analysis (TEA) guidelines, we then built a bespoke dynamic driver model (DDM)-based tool to support decision-makers. Hosted on the Akumen platform, the DDM approach to TEA elevates the process from the flaky and opaque world of spreadsheets, offering transparency and rigor, as well as the power of artificial intelligence (AI). This tool not only facilitates the evaluation of alternate processing futures, but it also enables the go-forward option to be shared with potential investors interactively so they can undertake genuine due diligence. Moreover, having assisted projects break out their scoping-study catch-22, the DDM remains a project team asset that can grow with the project, informing and supporting decisions as it passes through the rest of study-phase and then on into production. To illustrate these points, this paper focusses on a common scoping-stage decision around the inclusion of ore sorting, which is frequently hailed as a game-changer especially for struggling projects. By working through this decision, the paper both validates the importance of TEA, as flagged by the AusIMM’s, and demonstrates the benefits of realising it in the form of a DDM.
9:35 Techno Economic Evaluation of The Atlas Materials Process
Mike Dry, Owner, Arithmetek, Canada
This paper presents the results of a study comparing the techno-economics of producing nickel-cobalt hydroxide from saprolite for a new process being developed by Atlas Materials, against atmospheric tank leaching with sulphuric acid. The new route entails leaching saprolite with hydrochloric acid, precipitation of iron and aluminium hydroxides, precipitating the nickel and cobalt as a mixed hydroxide product, oxidation and precipitation of manganese, precipitation of magnesium and calcium as hydroxides and passing the remaining sodium chloride through a chlor-alkali section to regenerate hydrochloric acid and sodium hydroxide for recycle to the upstream parts of the process. Process modelling was used to generate detailed mass-energy balances for each route, then the balances were used to calculate preliminary estimates of the capital and operating costs associated with the processing routes examined. These numbers were used to examine the techno-economics of the two routes.
10:05 Innovative Technologies for Extraction of Nickel, Cobalt, and Manganese from Laterite Crusts
Maxim Sredki, Technical Director, ERM Sustainable Mining Services, Australia
ERM Sustainability Mining Services team (formerly CSA Global) has worked on innovative technologies for extracting nickel, cobalt and manganese from laterite mineralisation since 2018. This work commenced on Kazakh Ni-Co-cobalt laterite deposits with Ni grades from 0.3–1.3% (average 0.7% Ni) and cobalt grades around 300–500 ppm. In these deposits, Ni-Co mineralisation is comprised mostly of high-magnesium silicates, commonly nontronite, with minor amounts of Ni-Co in limonite. Modern processing of Ni-Co ores generally involves either pyrometallurgical or hydrometallurgical methods. Hydrometallurgical methods, including AAL, HPAL and heap leaching, are the most common. However, these conventional approaches have not been economic for the Ni-Co laterite deposits in the Urals and Kazakhstan due to the prevalence of Ni-silicate mineralisation and overall low grades. The successful development of in situ recovery technology for extracting copper and gold from regolith/weathering crusts was identified as a potential opportunity to extract Ni-Co from the Ni-Co enriched regolith in the Urals and Kazakhstan. Initial laboratory and pilot investigations – using sulfuric acid as the lixiviant – were completed on the Tochilnogorskoe, Kungurskoye and Rogozhinskoe deposits in the Urals. However, it was quickly recognised that sulfurous acid is a superior lixiviant for Ni-Co laterite deposits. This approach was successfully demonstrated in pilot tests on the Ekibastuz-Shiderty deposit in 2017. CSA Global prepared the first formal Scoping Study on the use of ISR at Ekibastuz-Shiderty using the Clean TeQ process to treat Ni-Co pregnant solutions using a combination of IX, SX and neutralisation of pregnant solutions. Subsequently, Kaznickel completed extensive ISR tests, over the course of 2021-2022, at the Gornostay Project using sulfuric acid as the lixiviant. This extended pilot test work resolved numerous issues in operating the test polygon and achieved a stable leaching regime. Kazniclel also developed an improved IX technology for processing pregnant solutions. At the same time, the research by the authors identified potential improvements for the extraction of Ni-Co from low-grade Ni-Co laterite deposits in Kazakhstan based on: Selective sorption of Ni on Lewatit TP-220 resin, followed by removal of iron from the resin using soft acid solutions, and desorption of Ni by 7-10% ammonium hydroxide, producing an eluate of Ni ammine complexes such as Ni(NH3)4(OH)2, Ni(NH3)6(OH)2 etc. These complexes are easily dissociated to produce Ni(OH)2, with ammonia recycled to the IX process. Improved heap leaching outcomes using enhanced agglomeration approaches that are more manageable than ISR. Poor permeability is the main issue with the heap leaching of clay-rich materials typical of regolith deposits. A polymeric additive that is stable with aggressive acid leaching was identified for improved agglomeration and permeability. The dynamics of heap leaching using this approach are much better than those of ISR. Processing using sulfurous acid was found to be favourable for the leaching of manganese from weathering crusts by both ISR and heap leaching. Mn grades in pregnant solutions were 50–60 g/L. MnO2 was produced directly from these solutions by electrowinning. However, Mn oxide mineralisation is often associated with elevated calcium, leading to gypsum permeability blockages (colmatation). In these cases, hydrochloric acid is better lixiviant than sulfurous acid, with Mn precipitated as the hydroxide. Recovery of the HCl by sulfuric acid improves the economics of this approach.
10:35 Evaluation of Carbonate and Phosphate-Based Biocement for in situ Barrier Operations
Pelin Polat, Researcher, Curtin University, Australia
In situ recovery (ISR) refers to the hydrometallurgical method for extracting metals through specifically designed chemical interactions. ISR is being employed widely in mining for recovering an increasingly diverse range of metals including uranium, copper, nickel, and gold. One of the foremost challenges in the ISR operation is to protect the surrounding geoenvironment and groundwater from the harsh lixiviants used in the process. Therefore, it is critical to establish an environmentally conscious strategy to build barriers around. This research aims to explore the potential of biogenically created carbonate- (as limestone, magnesium carbonate) and phosphate (as hydroxyapatite, struvite)-based barriers in various ISR-related environments. Created by natural biogeochemical activities of microbes in geological formations (microbialites, beach rocks), biocement has emerged as a potential biogeotechnical solution for a variety of engineering applications due to its significant advantages of low carbon footprint, low viscosity, and recyclability. While the majority of the research has focused on microbially induced calcium carbonate-based cement which faces challenges at low pH conditions, not much has been explored in developing low pH-tolerant phosphate-based biocement. In this study, a range of microbial metabolic pathways, roles of extra polymeric substances, substrates, and their impact on formation of struvite and apaptite biocements has been demonstrated. The impact of biogenic phosphate and carbonate cements on acid and alkaline lixiviant tolerance has also been analysed. Overall, the outcome of this research has significantly improved our understanding of microbially induced biomineralisation process and widened the scope of biocement barriers as containment in ISR-related environments.
11:05 Morning Tea in the Exhibit Hall
11:35 Clays Contained in Mineral Ores and Their Effects on Solid-Liquid Separation Processes
Andrew Hawkey, Diemme Filtration, Australia
Dry stacking of filtered tailings usually requires a low cake residual moisture to meet the specifications from geotechnical engineers. The growing demand for minerals has resulted in lower and more complex grades of ores being mined and processed. Many such ores contain varying amounts of clays. The filtration process can be hindered by the presence of clays and it’s important to understand the filtration characteristics of these ores at a very early stage in the flowsheet design. Other solid-liquid separation processes can be affected by the presence of clays, including thickening. Thickening, even in the beneficiation stage, can be severely compromised, leading to lower process efficiencies downstream (e.g., leaching). Poor thickening performance caused by non-ideal mineralogy (particularly clay content) can force the process designer to consider filtration as a more appropriate solid-liquid separation option (in some cases, even replacing counter-current decanting thickeners). Some clays affect solid-liquid separation processes more than others. A comprehensive characterisation of the ore that includes detection and identification of clay types is important. Standard physical-chemical characterisation of mineral slurries includes tests for density, solid concentration, and solid (and liquid) specific gravity. More thorough characterisation can include tests for yield stress, particle size distribution, and morphology, as well as element analysis and mineral phase detection. Some of these tests require sophisticated instruments and highly experienced technicians. Phyllosilicates (clays) are one of the most common components of mineral ores and tailings, together with quartz, feldspar, and other aluminosilicates. Their content is not necessarily predominant but their presence, even in small concentrations, can influence slurry behavior and filter cake permeability and moisture content. A comprehensive study of clay detection and quantification, including correlation with dewatering properties was recently carried out by Diemme Filtration’s R&D laboratory. Some of the results and conclusions of that study are presented here. The paper also uses real project examples to illustrate how the presence of clays in mineral ores can change the flow sheet design and influence the sizing of filtration equipment.
12:05 pm Microwave Processing of Ores—Commercial Realisation of a Step Change for the Minerals Industry
David Craig, Vice President, Jenike & Johanson Inc., USA
As ore bodies age and grades decline, increasingly higher embodied energy input is required for comminution to maintain production, which increases costs and the carbon footprint of these operations. A step-change in energy reduction is required to meet the future demand of these processes. Microwave technology has long been suggested as a route to significant energy reduction and enhanced recovery in mineral processing. Until recently, however, the work was at an academic level with little or no vision for deployment in the mining industry. We present for the first time a defined pathway to commercial application of microwave technology for the mining industry. This builds on our previous work which has successfully demonstrated this technology at over 150 t/hr. We consider the integration of microwave engineering with bulk solids handling at-scale, and present details of a route to commercial delivery. We will focus our paper upon the value proposition that this technology can deliver. We consider the impact of induced fractures on conventional grinding/flotation circuits, on the performance of leach systems, and on new flowsheets with the potential to deliver a paradigm shift in carbon emissions from mineral processing circuits.
12:35 Beyond Limits: Titanium Nitride’s Game-Changing Role in Hydrometallurgical Production
Evelyn Ng, Group Manager, Materials & Innovation, Callidus Process Solutions, Australia
The latest advancements in surface modification technology, tailored specifically for the demanding environments of the High-Pressure Acid Leaching (HPAL) and Pressure Oxidation (POx) industries, along with their trial outcomes, will be presented. The Callidus Group, comprising Callidus Welding Solutions (CWS) and Callidus Process Solutions (CPS), shall introduce innovative, engineering-based approaches that fortify equipment resilience and extend operational lifespans. Hydrometallurgical processes, such as HPAL and POx, heavily depend on titanium owing to its inherent corrosion resistance and mechanical properties. However, persisting challenges such as erosion, abrasion, and wear call for advanced solutions, as conventional methods such as thermal spray coatings on metal-seated ball valve trim prove inadequate. Collaborating with Deakin University, Victoria, Australia, CWS embarked upon a comprehensive exploration of the microstructure-property-performance relationship. This collaborative effort culminated in developing an advanced generation of Titanium Nitride, characterized by notable improvements in hardness, toughness, and corrosion resistance. This novel surface modification demonstrates enhanced resistance to sliding abrasive wear and exceptional corrosion resistance, addressing critical shortcomings in existing solutions. The culmination of this research partnership with CPS resulted in the development of a patented severe service ball valve trim named “FM-1500,” highlighting significant advancements in material performance. The presentation will elucidate the scientific journey from conceptualization to realization, spotlighting key findings from initial characterization studies, developmental milestones, and successful field trial outcomes.
1:05 Networking Luncheon
2:00 Chairperson’s Afternoon Remarks
2:05 More Out of Tailings: Metal and Acid Production, Circularity and Energy Transition
Darryl Harris, Head of Global Project Solutions Asia Pacific, Metso, Australia
The need to “extract more from less’ is not a byword that sits well in the mining industry. Head grade degradation, basically processing ever more ore to produce ever less final product with an inevitable increase in waste, is a fact for many operations. The need for more circular solutions required for the emerging energy transition (i.e. the demand for ever more non-ferrous and critical minerals) requires us to rethink what we can do differently. The processing of tailings from the copper ore processing offers significant potential to recover valuable elements like copper, cobalt, and nickel as well as to produce sulfuric acid for different applications in the fertilizer and metallurgical industry. Perhaps the time is right for a well proven industrial process to be part of the push towards a true circular economy? We intend to present our views on the renaissance of a technology value chain—the roaster-gas cleaning acid plant—widely used in the past and its applicability to the current scenarios. This process chain is capable of utilizing virgin pyrite ores as well as pyrite tailings, with a view to maximum extraction of valuable ferrous, non-ferrous and critical minerals, reducing acid mine drainage, production of clean energy as well as providing a ‘regionalized’ sulfuric acid supply. When these commodity flows are considered in total as revenue streams, return on investment is, in many cases positive, substantiating the claim that one can obtain ‘more out of ore’.
2:35 Diluent Selection and Its Impact on Performance
Jia Tian Lee, Regional Improve Engineer, ExxonMobil Pacific, Singapore
The diluent is an important component in the solvent extraction process. While its main role is to solubilise and carry the extractant, the composition and physical properties of a diluent can have a significant impact on the overall performance of the system. The choice of diluent can potentially optimize the solvent extraction process by improving extraction efficiency, phase disengagement, crud formation, and diluent losses. In selecting a diluent, trade-offs that exist between the diluent properties should be considered to come to an optimum solution. In addition, diluents constitute a large proportion of the mining chemicals used in a solvent extraction plant and hence its impact on the safety, health, and environmental aspects of plant operations cannot be understated. Over the years, diluent requirements have changed together with the continuous evolution of safety and environmental standards in the mining industry. The right diluent will enable a safe working environment without compromising technical performance. ExxonMobil’s Escaid fluids have developed over the years to meet the evolving needs of the mining industry. They have been used globally in the extraction of copper, nickel, cobalt, uranium, and other valuable metals. The Escaid fluids portfolio features product grades with a range of volatilities and chemical types to support mining operations. The presentation will compare several diluents to provide insights on how the composition and properties of the diluent influence the solvent extraction process. The safety, health, and environmental characteristics of the diluents will also be examined to show how the choice of diluents can help enhance industrial hygiene, improve personnel safety, and potentially reduce environmental impacts.
3:05 Benefits of GTL G80 Mining Diluent in Copper SX for Low- and High-Grade Copper Ore
Miguel Rivera Torrente, TS&D Specialist, Shell Global Solutions International, The Netherlands
Shell GTL G80 is a synthetic, aliphatic mining diluent supplied by Shell into copper solvent extraction (CuSX) operations which represents the 4th generation of SX Diluents. G80 is produced from natural gas via the gas-to-liquids (GTL) process, resulting in a mixture of hydrocarbon distillate different from common market diluents. In this work, we present the benefits of using G80 as the organic phase with various extractants of the LIX and ACORGA brands. Among others, good phase disengagement, copper loading, and extraction/stripping kinetics were observed in laboratory tests carried out under common operating SX conditions. This was associated to the hydrocarbon composition of GTL G80, which consists almost exclusively of linear and lightly (methyl, ethyl) branched iso-paraffins, as opposed to other diluents which may contain naphthenes and aromatics. Furthermore, the effects of high extractant concentration, commonly used for the recovery in Sub-Saharan oxidic deposits, were also studied. Specifically, we evaluated the impact of ~30%v/v concentration of various oximes in viscosity at different temperatures. Despite the low aromatic content of GTL G80 (< 300 ppm), the range of viscosities determined by standard methods was acceptable for most SX operations. In addition, different lab tests showed that the evaporation rate was lower than common aromatic and dearomatised diluents, likely resulting in less top-up necessary. These different parameters were benchmarked against an aromatic (20%) diluent, as well as aliphatic diluents produced from mineral oil.
3:35 Afternoon Tea in the Exhibit Hall
4:05 Investigating the Impact of High Temperature Agitation Leaching on the Rate of Oxime Degradation
Andrew Nisbett, Global Project Manager, BASF Mining Solutions, USA
Agitation tank leaching is a widely used method in the African Copperbelt to facilitate the rapid dissolution of copper from mid- to high-grade copper ores. As ore grade has begun to decline and the relative abundance of secondary sulfide mineralisation is increasing, many plants are now beginning to treat calcined ore from a roaster to increase the rate of recovery of copper. This process is causing an increase in the temperature of the pregnant leach solution (PLS) produced. The extraction step occurs in relatively mild acid conditions of 1-10g/L sulfuric acid, which is significantly lower than the 150-200g/L sulfuric acid level that copper solvent extraction (SX) reagents are contacted with in the stripping stage of most processes. However, the higher temperature range of 40-60°C is thought to be linked to an observable increase in the acid-catalysed hydrolysis rate of the oxime reagents commonly used to selectively extract the copper from the PLS after agitation leaching. This study shows the results of an experiment conducted to investigate the rate of hydrolysis observed from sustained contact with the PLS produced from these leaching conditions and temperatures. The results will be contrasted for the most common types of extractants currently used in the market and we will discuss the potential implications of those results.
4:35 Mass Transfer Intensification Implementing the Use of Static Mixers in Co/Ni Solvent Extraction
Derik Van Der Westhuizen, Research Scientist, North-West University, South Africa
Residence time plays a crucial role in any solvent extraction process. The mass transfer rate is significantly increased by reducing the oil droplet size of an oil-in-water dispersion. Therefore, residence time reduction through increased mass transfer rates is vital for optimizing these processes. Recently, there has been a renewed interest in using static mixers to reduce the droplet size of these dispersions. Several studies have documented the efficacy of static mixers in reducing droplet size in these dispersions. However, characteristic equations of these static mixers have yet to be sufficiently developed. These equations describe the inherent efficiency of different static mixers in various separation systems. This study seeks to develop characteristic equations for different static mixer configurations in a Co/Ni separation system. The parameters incorporated in these equations include the Sauter mean diameter of the oil droplets (𝑑32), the diameter of the pipe (𝐷), the Weber number (𝑊𝑒), Reynold’s number (𝑅𝑒), and the number of static mixer elements used in the system (𝑛𝑒). The study considers the development of correlations with pre-determined fitting parameters (𝛼, 𝛽, 𝛾, 𝛿) descriptive of each unique static mixer design. The characteristic equations take the following form: 𝑑32 = 𝛼𝑊𝑒𝛽𝑅𝑒𝛾𝑛𝑒𝛿 This study provides an approach to developing these characteristic equations using droplet size reduction in a Co/Ni solvent extraction system. The droplet size reduction was determined using existing settling velocity correlations. These characteristic equations were developed in various flow regimes for small-scale and largescale applications. After creating these equations, a computational fluid dynamics (CFD) model was constructed in Star-CCM+ to verify the validity of these equations under different conditions. The research conducted provides empirical confirmation that static mixers are not only able to decrease residence time in solvent extraction processes but also that static mixers exhibit different behavior in different systems. The research results represent a further step towards optimizing solvent extraction processes using static mixers.
5:05 Production of Battery-Grade Nickel and Cobalt Sulfate from Nickel Laterite Ore
Kaixi Jiang, Chief Scientist, BGRIMM Technology Group, China
High-pressure acid leaching process (HPAL) is currently mainly used to treat nickel laterite ore; above 95% of Ni/Co leaching rate can be achieved by it. A two-stage pressure leaching process is developed to treat nickel laterite ore. After HPAL, instead of flash evaporation, the leached slurry is directly sent to the high-pressure neutralization unit and continues to react with the added saprolite slurry. It utilises the waste heat of 1st HPAL to neutralise residual sulfuric acid at slightly lower temperatures and pressures, as well as allowing newly generated iron to precipitate and release acid in the form of hematite, while achieving enhanced leaching of saprolite. Meanwhile, it further promotes the hydrolysis of Al3+ and reduces the concentration of impurity Al in the neutralised solution. The pressure-leached solution is subsequently treated by Fe/Al removal and Ni/Co precipitation. Mixed nickel-cobalt hydroxide (MHP for short) is obtained and used as raw material for refining. The process for producing battery-grade nickel sulfate and cobalt sulfate from MHP generally includes sulfuric acid leaching, Fe/Al removal, impurities removal by SX, nickel and cobalt separation by SX, etc. At present, Fe/Al removal is mainly conducted by lime milk. This process is widely used, but there exist problems as follows: high Ni loss (~1.5%) due to high residue amount with high Ni content (6-12%); saturated Ca ions are introduced into the solution. Calcium sulfate crystals will precipitate during P204 impurities removal, which will cause blockage and stoppage. In addition, most factories adopt 2 series of P507 SX to separate Ni/Co/Mg, which will lead to higher CAPEX and OPEX. A new process for Fe/Al removal and Ni/Co/Mg separation by SX is developed. Nickel/cobalt/manganese-based (MHP is preferred) neutraliser is used to remove Fe/Al, followed by L/S separation, the solution is sent for further impurities removal, the residue conducted by acid re-leaching Fe/Al removal by lime milk for recovering Ni/Co and Fe/Al open circuit. In P507 SX, Ni saponification is used to control Na from entering to raffinate. After extraction by P507, Co and Mg are completely extracted to organic phase. Raffinate is battery-grade nickel sulfate solution. The loaded organic is scrubbed by many stages of acid solution scrubbing to remove Mg. Finally, the loaded organic is stripped by acid to obtain battery-grade cobalt sulfate. In this case, Ni/Co/Mg is separated in one SX series. This new process reduces the dosage of lime milk, the number of calcium ions introduced into the system, and the losses of Ni/Co. The separation of Ni/Co/Mg is simplified as well.
5:35 Session Break
6:30 Pre-Dinner Conference Reception (Sponsorship Opportunity Available)
7:00 Sponsor’s Welcome 
7:00 Networking Dinner (Sponsored by JordProxa)
10:00 Close of Day
Wednesday 29 May
8:00 am Registration & Arrival Tea
8:30 Chairperson’s Opening Remarks
8:35 Halion Process: Breakthrough in Halide Leaching
Dave Sammut, Founder & Managing Director, Loop Hydrometallurgy, Australia
The extraction of minerals using chloride lixiviants has been thoroughly investigated and proven to offer major advantages in low-cost, highly versatile minerals processing, with extremely low carbon footprint. Loop Hydrometallurgy continues to innovate in advanced halide-based minerals processing. The Halion Loop employs mixed halides to extract copper, nickel, cobalt, lead, zinc, silver, gold, REEs and other metals from a broad range of concentrates, tailings, and industrial waste materials. It operates at atmospheric pressure and less than 100 degrees Celsius, with no noxious gas emissions and no liquid effluents. In its latest breakthrough, Loop Hydrometallurgy has proposed an entirely new form of leaching that significantly extents the capabilities of economic and efficient processing for refractory materials. This new form of leaching has undergone successful initial trials in the extraction of cobalt from pyrite tailings. This new technology offers the prospect of reagent-less leaching for materials that would otherwise be expected to be highly acid- or alkali- consuming by conventional hydrometallurgical processes. By extending the capabilities of the extraction step, the Halion Loop has also been shown to enable significant efficiencies to be captured upstream of the concentrate, at the mine and mill. This paper will discuss the outcomes of initial studies of the breakthrough technology, as well as some of the broader potential applications in critical and battery minerals, gold processing, the stabilization of arsenic, and beyond. It will also discuss the outcomes of economic analysis for processing non-traditional concentrate feedstocks, including low grade and polymetallic bulk concentrates, and materials containing high levels of arsenic.
9:05 A New Vortex Erosion Test Methodology for Evaluating Erosion Resistance
Bon Nguyen, Research Engineer, CSIRO Mineral Resources, Australia
Vortices are often generated in industrial slurry flows where flow disturbances exist. These can include bolt heads, weld beads, temperature sensors, and other similar flow disturbances. The vortex flow generated typically leads to changed particle impact angles and velocities creating increased localised erosion. Such localised erosion can lead to the premature writing off of slurry handling equipment. Recent work at CSIRO’s Fluids Engineering Laboratory has built on previous fundamental erosion studies to develop a standardised methodology for evaluating the erosion performance of different classes of materials under vortex erosion conditions. The fundamental experiment design is a flat plate sample with a cylindrical obstacle protruding from it to provide the vortex generation at the junction of the sample and the cylinder. The cylinder has a ceramic structure to minimise its erosion thus keeping the geometry of the erosion creating geometry constant. These samples are then mounted in the large-scale CSIRO slurry erosion test rig and exposed to a sand-water slurry flowing at 3.6 m/s, typical of industrial slurry applications. The erosion on each sample is measured using a coordinate measurement machine (CMM). The relative erosion of alloy steels, white iron, ceramic materials, and a polymer material under vortex erosion conditions was tested using this methodology. The erosion results were then compared with the ceramics and polymer showing significant resistance to the vortex erosion. These results are discussed in terms of the erosion test methodology and improved slurry flow designs to mitigate erosion, such as modified flow geometry to reduce flow separation and vortices.
9:35 Modularization of HPAL and POX Units in Nickel & Cobalt Industries
Si Peng, CTO, Morimatsu Energies & Materials, China
The application of the pressure leaching process, especially HPAL and POX, in nickel and cobalt industries has seen dramatic growth in recent years, driven by the rapid development of the EV industry. In the past 3 years, more than 20 autoclaves have been delivered to Indonesia for HPAL projects, all of which were successfully ramped up and exceeded the production target in less than one year. Meanwhile, more and more POX projects are being built in China, Indonesia, and South Korea, with nickel matte from laterite as the feedstock. The success of HPAL projects in recent years is based on the lessons learned on engineering, commissioning and ramp up of previous HPAL projects in Australia, Papua New Guinea, Philippines, New Caledonia, Turkey, and Madagascar. Although the POX of nickel matte from laterite is newly introduced, the previous POX projects treating nickel matte from nickel sulfide in China and Canada and MS from laterite in Australia, Madagascar, and China, provided the engineering templates and commissioning experience. Different from previous projects, the process and layout of recent HPAL and POX projects were more like templated, with only distinctions on sizing of equipment, pumps, valves, and pipes. Modularization of leaching plants are hence quite suitable for HPAL and POX projects in the nickel and cobalt industries, providing schedule certainty, cleaner and safer environment, skilled worker team, reduced site labor and peak, shorter installation time on site, lower environmental/socioeconomic impact, and less disturbance by local situation. For those inland projects subjected to transportation limitations of large size modules, a high degree of prefabrication will be an alternative solution.
10:05 Extending Autoclave Service Life beyond the Third Decade
Evelyn Ng, Group Manager, Materials & Innovation, Callidus Process Solutions, Australia
Autoclaves are critical fixed assets integral to the high-pressure acid leaching (HPAL) process. Traditionally, these vessels are engineered with a thirty-year operational lifespan, aligning with the projected lifespan of mining operations. Throughout this designated lifespan, regular maintenance efforts are directed toward repairing corrosion and erosion damage within the autoclave lining. However, a critical knowledge gap exists regarding the viability of extending the autoclave’s service life beyond its designed duration. Despite the initial design parameters, instances arise where the operational lifespan of an autoclave needs to be prolonged, particularly when the mine’s lifespan is extended. Comprising formed carbon steel and explosion-bonded titanium, the autoclave’s structure blends mechanical strength with cost-effectiveness. The titanium-clad lining is a vital protective layer, shielding the vessel’s interior against high-temperature acidic slurry’s corrosive and erosion effects. Given the considerable size of autoclaves, their construction entails multiple plates of carbon steel and explosion-bonded titanium, meticulously shaped to form the vessel’s cylindrical body with hemi-heads at each end. The interior is rendered seamless by strategically welding titanium batten strips, ensuring a tight seal containing the pressurised acidic slurry. Routine maintenance shutdowns are inevitable to address issues such as leakage, corrosion, and erosion within the autoclave lining. Repair procedures involving the removal and replacement of batten strips and subsequent welding pose concerns regarding the impact of the titanium cladding’s material properties. Notably, the potential formation of intermetallic compounds and consequent cracking in the autoclave wall lining remains a looming threat. This presentation aims to unveil findings regarding the critical threshold of titanium cladding thickness that must not be compromised to mitigate the risk of intermetallic formation and subsequent structural integrity issues. By offering essential insights into long-term maintenance strategies for autoclaves, this research bridges the knowledge gap essential for ensuring the sustained efficiency and safety of HPAL processes.
10:35 Morning Tea in the Exhibit Hall
11:05 Modelling and Simulation of Nickel Solution Purification in Industrial Jarosite Autoclaves
Johann Steyl, Director, Dynamet Insights, South Africa
This paper describes how a hybrid first-principles—machine-learning (FP-ML) modelling and simulation platform can help to understand and improve complex industrial processes. Nickel solution purification, predominantly via ammonium jarosite precipitation in a series of autoclave stages, is used as a case-study example to demonstrate the benefits of this approach to the industry. It also provides an implementation platform where these benefits can be made accessible to a wider technical team in an operational environment. The model inputs are the logged inflow stream flows and upstream block states. An initial modelling phase identified info gaps in the operational chemical suite, which prompted a short sampling campaign to measure the key species profiles over a pre-selected case-study period. Since precipitation mechanisms are complex and difficult to interpret via batch experimentation, only this plant data and the hybrid modelling approach were used to digitally capture the key information. The FP modelling construct is based on acausal mass-energy balance equations, which take care of the dynamic interactions of each inventory block with its neighboring blocks. Within this FP framework, phenomenological equations were added, and ML algorithms trained to capture the observed case-study period behavior. This workflow methodology is discussed in the paper and only relies on basic chemistry, measurement, and understanding. The advantage of this approach is that the data science blocks can deal with microscopic-scale complexities, while the combined model generalises the behavior so that it becomes predictive. Measured vs. predicted trends are presented in the paper, demonstrating that this model qualifies as a true digital twin (DT) and that it can be used to optimise control and improve operating strategies, amongst others. A compiled application product (App) version of the DT, with user-friendly frontend, was therefore packaged and distributed to the plant engineers for use on a day-to-day basis.
11:35 From Fire Assay Nickel Sulfide Collection Waste to Nickel Hydroxide
James Tshilongo, Executive Manager, Analytical Chemistry Division, MINTEK, South Africa
The present research describes a novel methodology for converting refuse materials generated during a novel fire assay procedure, particularly those originating from nickel sulfide (NiS) collections that contain nickel (Ni), into nickel hydroxide (Ni(OH)2), which is considered to be highly valuable. The procedure begins by gathering waste materials that contain Ni and are subsequently subjected to rigorous separation and sorting methods to extract the specific Ni compounds of interest. Solvent extraction is utilised in conjunction with 5,8-diethyl-7-hydroxydodecan-6-oxime (LIX 63-70) procedures to extract copper (Cu) selectively. A controlled pH adjustment is performed on the purified Ni solution using lime. Iron (Fe) impurities are eliminated at pH 2.5-3, and Ni(OH)2 precipitates at pH 6. The solid product obtained through filtration and dehydration is subjected to stringent quality control analyses, which validate the crystalline β-Ni(OH)2 structure via X-ray diffraction (XRD) and Fourier transform infrared (FTIR) characterisations, as well as chemical analysis via inductively coupled plasma-optical emission spectroscopy (ICP-OES). The process of converting waste materials into crystalline β-Ni(OH)2 not only recovers valuable resources but also efficiently eliminates Fe impurities, thus adhering to sustainable practices and environmental concerns.
12:05 pm Technology Selection and Flow Sheet Optimisation for Nickel and Cobalt Sulfate Crystallisation Plants
Nipen Shah, Head of Sales, JordProxa, Australia
The safety and performance of lithium-ion batteries are deeply influenced by impurities in their precursors, necessitating the production of the battery materials such as nickel sulphate and cobalt sulphate to the highest purity. The declining prices of battery materials have put pressure on the producers to optimise the capital and operating expenditures to make the projects economically viable. Crystallisation is the most important final purification step in producing high purity battery grade products. The optimal design of nickel and cobalt sulphate crystallisation plants hinges on key technological choices and flow sheet optimisations. A properly designed crystalliser producing large, well-formed crystals allows for improved washing to enable the achievement of the highest purities possible. This paper evaluates the efficacy of Forced Circulation (FC) versus Draft Tube Baffle (DTB) crystallisers, evaluating their respective merits in achieving desired purity levels, capital costs, and operational efficiency. A further technical innovation is the incorporation of mechanical vapour recompression (MVR) technology which results in a significant reduction in the overall energy input per ton of product when compared with steam heated designs. This paper also investigates the trade off between the capital and operating expenditures for both these heat input options. This paper describes crystalliser design features to produce battery grade nickel sulphate hexahydrate and cobalt sulphate heptahydrate products, and will compare the operating conditions, crystalliser types, preferred energy source, control of product purity, and trade-off between capital and operating costs.
12:35 Networking Luncheon
1:30 Chairperson’s Afternoon Remarks
1:35 The Use of Ion Exchange Resins to Produce High-Purity Cobalt and Nickel Sulfate
Johanna van Deventer, Technical Sales Manager, Puralite, South Africa
Ion exchange is widely used in hydrometallurgical operations for the recovery and purification of valuable metals, such as nickel and cobalt. The growth of the electric-vehicle market has resulted in an increase in demand for metals used in batteries. Although commonly referred to as lithium batteries, appreciable amounts of cobalt, nickel, manganese, and other metals form part of these batteries. The metal-salts used in the manufacturing of EV batteries may be obtained from mining operations. Recycling of used batteries is a growing source of material, with recycling being mandated by law around the world. Regardless of the origin of the metals, there are a number of impurities present in the nickel/cobalt liquor that need to be removed to low levels, to produce precursor materials that are suitable for the production of high-quality batteries. Such impurities typically include iron, uranium, copper, zinc, nickel, cobalt, bismuth, and antimony. Special chelating resins have a high affinity for specific elements, allowing the selective removal of low levels of impurities from a background of highly concentrated valuable metal. Solvent-impregnated resins have been added to this group more recently, expanding the choice of sorbent. In addition to choosing the right type of resin for the job, manipulation of the operating conditions, such as pH, provides additional selectivity. Choosing the optimum contactor design is critical to ensure consistent quality while at the same time being economically feasible and taking due consideration of incorporation of the ion exchange unit operation in the overall flowsheet. This article takes a closer look at various applications of ion exchange in the production of high-purity cobalt and nickel sulfate.
2:05 Enhancing Nickel Laterite Processing Using Electrochemical Separation to Extract Sulfuric Acid from Magnesium Sulfate Solutions
Mohamed Ibrahim, Researcher, University of Queensland, Australia
Nickel holds a broad spectrum of applications, with its production expanding to meet the surging demand, particularly in energy storage applications. Extracting nickel from laterite ores via hydrometallurgical methods demands a substantial volume of sulfuric acid, mainly due to acid-consuming minerals like magnesium silicates. This reaction yields magnesium sulfate waste solution, posing environmental concerns. To address this, electrochemical separation offers a solution, producing acid from these waste solutions for onsite reuse, enhancing nickel recovery. Additionally, the resulting magnesium hydroxide can serve for carbon capture or as a precipitant in the nickel process. In our study, a single membrane electrolyser was employed to convert magnesium sulfate solutions into sulfuric acid and magnesium hydroxide precipitate. We evaluated the electrolyser’s performance in terms of faradaic efficiency, acid production energy intensity, current density, and sulfate recovery extent. We varied the electrolyser potential and the initial concentrations of catholyte and anolyte for evaluation. Results indicated that maintaining 90% faradaic efficiency is feasible with a starting MgSO4 concentration of 1M or lower and a 4V electrolyser potential, up to an anolyte concentration of 0.16M H2SO4. However, higher voltages, concentrations, and conductivities across the anolyte and catholyte negatively impact faradaic efficiency due to water splitting. While a high electrolyser potential enhances sulfate transport, it also leads to excessive Mg (OH)2 precipitation, scaling the cathode, posing operational challenges.
2:35 Development in Battery Metals Solvent Extraction Process Design and Simulation
Hannu Laitala, Chief Metallurgist, Hydrometallurgy, Metso Outotec, Finland
During the last decade we have seen a big demand increase for battery metals like nickel, cobalt, manganese, and lithium. At the same time, the market is demanding higher quality products. Higher quality requirements put pressure on the process design practices. Process design practices must be developed so that one can not only predict the amount of production, but also the quality of the production. This means, that modern process design for a solvent extraction plant must be done using a process simulator. A modern SX plant’s accurate mass balance can’t be calculated manually. A solvent extraction process simulator must be able to calculate not only the main process flows and their compositions, but also the solvent extraction circuit’s performance with different feed compositions and amounts. The simulator must also be able to predict how the critical impurities behave in the different circuits. One very important detail is also to model the entrainments in the circuits. Especially in battery metals solvent extraction processes, accepted impurity levels are given in mg/L and this means that solvent extraction entrainments have a big impact on how well the SX circuit is performing. Also, an SX simulator must be able to predict how the changing process conditions in the different solvent extraction stages changes the chemical equilibrium. An organic phase’s metal loading in different stages also affects the chemical equilibrium calculation. Highly loaded organic phase extracts metals differently than a partly or not-loaded organic phase. Simulator design is also very fast. For a standard SX process, a simulator model can normally be done in a few hours. A little bit more complicated case can be simulated in few days and even a totally new simulator can be done in less than a week if the base information is readily available with superior accuracy compared to the process mass balance calculations done without a simulator. Current simulators can also predict problems in SX circuits. Metso’s HSC Sim process simulator is an excellent tool for SX process simulation. HSC Sim is one of the few process simulators where you can simulate both phases, aqueous and organic, in changing process conditions and given entrainments in every stage and combine the different SX stages to a fully functional SX process. Today HSC Sim models have been used in the process design of several operational SX plants. Several SX plants are being constructed where process simulation has been done by HSC Sim.
3:05 Afternoon Tea in the Exhibit Hall
3:35 Impurity Removal Piloting for The TECH Project – Manganese, Zinc and Calcium Removal, Gypsum Management, and Transformation and Purification SX for Production of High Purity Cobalt Sulfate
Boyd Willis, Chief Metallurgist, Hydromet Consulting, Australia
The Sulfate Refinery in the Queensland Pacific Metals’ TECH Project will treat a crude mixed hydroxide precipitate by sulfuric acid leaching, followed by aluminum precipitation, impurity removal, cobalt solvent extraction, nickel solvent extraction, and crystallization of high purity nickel and cobalt sulfate products. All sulfate refinery circuits were piloted sequentially during 2023 at Lakefield, Ontario by SGS Canada. This paper focusses on the impurity removal circuit which consists of two solvent extraction (SX) circuits that use di (2-ethyl hexyl) phosphoric acid (D2EHPA), dissolved in a high flashpoint aliphatic diluent. These two circuits are Impurity Solvent Extraction (ISX) and the Transformation and Purification (TSX and PSX) circuit. In ISX, impurity metals, including manganese, zinc and calcium, are preferentially extracted over cobalt and nickel. Extraction is followed by scrubbing with sulfuric acid prior to sequential manganese stripping and zinc stripping, both with sulfuric acid. A bleed of zinc-stripped organic is directed to iron stripping using oxalic acid. The ISX raffinate is forwarded to cobalt solvent extraction (CSX) for cobalt recovery. In transformation, a bleed of the ISX stripped organic is transformed into cobalt-loaded organic. In purification, cobalt-loaded strip liquor (LSL) from CSX is contacted counter-currently with the cobalt loaded organic. The impurity metals from the cobalt LSL displace cobalt from the organic and the raffinate (purified cobalt LSL) is forwarded to cobalt sulfate heptahydrate crystallization. The impurity removal pilot plant design, operation and results are presented. The feed to ISX is calcium-saturated, leading to gypsum formation in parts of the circuit. The paper discusses the strategies for gypsum management developed during piloting. Purification increased the Co:Mn ratio from 540:1 to >600,000:1, the Co:Zn ratio from 6,000:1 to >66,000:1, and the Co:Cu ratio from 12,000:1 to >50,000:1, and the maximum Ca and Fe in purified cobalt LSL feed to crystallization were determined to be 10 mg/L and 1.5 mg/L respectively.
4:05 Selective Co-Extraction of Ni & Co from High-Ca/Mg Solutions
Shengxi Wu, Lecturer, Central South University, China
Ni & Co extraction and purification is a critical operation for the preparation of high-purity Ni & Co salts from various raw materials, especially in the NCM battery industry. However, due to the insufficient separation coefficient of industrial classic extractants, traditional Ni(Co) recovery and separation process has to go through operations of impurities removal extraction (Ca, Mg, Cu, Zn, Fe, Al, etc.) with D2EHPA, Co extraction with HEHEHP, Mg extraction with Cyanex 272, Ni extraction with HEHEHP in the case of spent LIBs, suffering issues of process redundancy, large reagent consumption, and high cost. Even worse, loaded organic phase in procedures of Co extraction, Mg extraction require more than 8-stage acid scrubbing and produces considerable MgSO4 wastewater containing small amounts of Ni(Co). In current industry, most plants adopt Na2S precipitation method to remove and solidify Ni(Co) into sulfides which releases toxic H2S gas and generates Ni(Co)-Mg sulfide solid waste. Then, preferential extraction of Ni(Co) from Ca(Mg) concentrated solutions would be an ideal solution for these issues, based on what a synergistic extraction organic solvent consisting of acid and esters (HBL-116) was proposed. In single-stage tests, high separation coefficient of βNi/Mg>500 was obtained under optimal conditions, moreover, excellent separation performance was also achieved in industrial application. For example, selectively and completely extracted 1.0~5.0g/L Ni(Co) from 40~60g/L Mg contained scrubbing solution was achieved by HBL-116 extraction production line in Guangdong Fangyuan New Materials Group Co., Ltd., leaving <1mg/L Ni(Co) in raffinate and produced 35~50g/L Ni(Co) stripping solution with Mg<0.1g/L. In addition, the acid and alkali consumption is about 105~110% of stoichiometric ratio for Ni(Co) cation exchange depends on the concentration of Ni(Co) in feed solutions. According to the feedback from applied plants, HBL-116 shown excellent separation performance for Ni(Co) to Mg.
4:35 CLOSING PANEL DISCUSSION
5:05 Close of Nickel-Cobalt-Copper Conference
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