12th International Copper Conference

Table of Contents

1. Mineral Processing

   1. Frontmatter

   2. An Alternative Approach in Modeling Flotation Performance Based on the Grade Recovery Relationship at Batu Hijau

      D. Varianemil, L. Gurieff, A. Abdurrahman, S. Cross

      Abstract

      Over the years defining grade–recovery curves numerically has often proved challenging with many a hand drawn curve being interpolated to generate grade and recovery estimates for forecasting or budgeting. Grades and recoveries are the most basic method of measuring separation performance and are routinely calculated and reported. But the challenge becomes comparing grades and recoveries under varying processing conditions to assess which conditions produce the best results. Often an improved recovery comes at the expense of a loss of concentrate grade, or vice versa. Sometimes both grade and recovery are affected by changes in feed grade, and this takes no account of finding data for comparison where other influential factors are relatively constant and so can be concluded not to have affected the results. Obviously, the dilemma is deciding whether a genuine improvement in the grade–recovery relationship has occurred, or has yield been traded for quality (or vice versa). A simple separation model has been used to review plant operation data from the Batu Hijau copper/gold processing plant. The model enables grade–recovery relationships to be expressed numerically making performance at different operating conditions easy to compare, and in many instances, also allows the differences in performance to be quantified. Over 20 years of plant data has been reviewed using the separation process model. Comparison of grade–recovery relationships has improved understanding of the impact upon plant performance when treating ore tarnished to varying degrees. The impact of varying feed grade upon the grade–recovery relationship has also been quantified.

   3. Innovative Technology Integration for Transforming Metal Production in Copper and Copper–Gold Operations

      Barun Gorain, Preetham Nayak, Nicolas Miranda

      Extended Abstract

      Worldwide, copper and copper-gold operations are increasingly challenged by declining ore grades and rising mineralogical complexity. For example, the average copper head grade in Chile has decreased by 30% over the last 15 years. Moreover, the world’s largest copper concentrator, Escondida, has seen its head grade decline significantly—from approximately 2.5% copper in the 1990s to around 0.5% today (Erismann in Mining Journal, 2022). In response to these challenges, the mining industry has processed higher ore volumes; over the past 10 years, the ore sent to concentrators worldwide has increased by 1.1 billion metric tons, representing a 44% growth (McKinsey & Company Mining 2030: How the industry is adapting to declining ore grades and rising ore volumes, 2023). To handle this increased throughput, larger comminution and flotation equipment are being installed. For instance, flotation cell volumes as large as 630 m³ are now operating at the Buenavista del Cobre (BVC) concentrator in Northern Mexico (Metso in Scaling up: the adoption of large flotation cells in modern concentrators, 2022), while new non-mechanical cells such as Woodgrove’s Staged Flotation Reactor (SFR) and Eriez’s Hydroflot are also being adopted.

      These industry trends underscore the necessity for technological integration that not only addresses the increased processing volumes and equipment demands but also enhances recovery efficiencies and mitigates environmental impacts. This paper presents a comprehensive strategy that integrates three synergistic technologies:

      1.

      Integrated Ore Sorting: Enhances head grade through pre-concentration and rejection of waste early on in the value chain.

       

      2.

      Advanced Flotation Recovery (FLOT-ART): Improves metal recovery in flotation operations by employing advanced reagent chemistry, optimized cell hydrodynamics, and bank operations along with an ore-specific circuit control strategy

       

      3.

      Eco-Friendly Desulfurization with Mixed Chloride-Based Technology: Treats tailings to reduce acid rock drainage (ARD) potential and recovers additional metals.

       

      These three technologies are leveraged and integrated as per the need of an individual operation. It is not necessary to utilize all three technologies at once, rather a stage-wise approach is most appropriate in many cases. Some applications of these technologies along with benefits are provided in this brief overview.

   4. Flotation Launder Retrofit Impact on Copper Concentrators

      Guillermo Bermudez, Christian Cardoso, Aino Saikkonen

      Abstract

      Efficient froth collection is crucial for optimizing flotation circuit performance, as it can directly impact both mineral recovery and profitability. Insufficient froth management can lead to the loss of valuable minerals to tailings, resulting in significant financial losses. In recent years, the demand for extracted metals has grown, driving higher throughput in mineral processing plants and consequently the use of larger flotation cells. These bigger cells have led to increased froth surface areas and longer transport distances, which have been credited for hampering froth collection. To address these challenges, optimizing the froth area with the appropriate launder arrangement can be essential. Nowadays, there are different froth collection designs available; however, several studies have shown that effective results in enhancing froth management in large flotation cells have been accomplished by using center launders. This is mainly due to their design, allowing increased crowding while minimizing froth transport distance. Implementing these efficient center launders is well adapted to meet flotation needs, as they can be integrated into both greenfield and brownfield projects. Greenfield implementations can be achieved during the design phase prior to manufacturing. In the case of brownfield projects, installing center launders can be straightforwardly accomplished during planned shutdowns of concentrators. This paper examines the effectiveness of center launder retrofits in existing operations to improve metallurgical recovery in large flotation cells. Field implementations across various sites have been studied, showing statistically significant improvements in copper recovery rates. These improvements have been observed with different amount of center launder installations down the flotation bank. The impact of different center launder retrofits throughout the copper industry is discussed in detail in terms of metallurgical recovery, operational parameters, and return on investment.

   5. Evaluating the Influence of Goethite Nanoparticles on the Flotation Performance of Chalcopyrite and Enargite: A Preliminary Study

      Akbarshokh Ulmaszoda, Eska Putra Dwitama, Hajime Miki, Keiko Sasaki, Gde Pandhe Wisnu Suyantara

      Abstract

      This study investigates the impact of goethite (α-FeOOH) nanoparticles on the flotation behavior of chalcopyrite and enargite, two significant minerals in copper beneficiation processes. Flotation experiments were conducted using a column-type apparatus for chalcopyrite and enargite. The results demonstrated that goethite nanoparticles significantly hindered the flotation of both minerals. For chalcopyrite, the addition of 30 mg/L goethite nanoparticles reduced flotation recovery from 93 to 15%. Similarly, enargite recovery decreased from 94 to 22% and 16% with 30 mg/L and 50 mg/L goethite nanoparticles, respectively. Surface analyses revealed that goethite nanoparticles adsorbed onto the mineral surfaces, rendering them hydrophilic and consequently reducing their floatability. These findings suggest that goethite nanoparticles can act as effective nanodepressants for both chalcopyrite and enargite flotation. This study contributes to the development of novel separation techniques for complex copper ores, potentially offering more efficient and environmentally friendly alternatives to traditional flotation processes.

   6. Investigation of HydroFloat® Coarse Particle Flotation on an Iron Oxide Copper Gold Deposit

      Rahul Singh, Maoming Fan, Ryan Letkiewicz, Jie Dong, Manqiu Xu

      Abstract

      Given a growing shortage of high-grade copper resources and the resultant increase in demand for copper, a global push to improve safety and reliability of tailings storage facilities, and an increased focus on environmental stewardship, the mining industry is in search for innovative solutions to improve the efficiency, reliability and safety of its operations and new assets. One such solution is Eriez’ HydroFloat Coarse Particle Flotation (CPF) technology. As conventional flotation technologies are unable to efficiently recover coarse particle sizes due to their inherent metallurgical and operational limitations, the CPF increases the maximum floatable particle size using a combination of flotation and hindered bed separation fundamentals. These principles increase the flotation rate of both coarse and partially liberated particles otherwise lost to tailings in conventional flotation cells. As a result, the CPF can be used to optimize metal recoveries, flotation grind size, mill throughput and/or tailings water recovery. To investigate these potential benefits at its Salobo (Brazil) operation, Vale facilitated the completion of laboratory HydroFloat CPF testing on an iron oxide copper ore. Testing was carried out using coarse gangue rejection and tailings scavenging flowsheet modifications, with the intentions to maximize primary grind size and global metal recoveries, respectively. This paper summarizes the test results within both circuit configurations and highlights the relationship between primary grind size and flotation performance using the novel CPF technology.

   7. McNulty Curves—An Update and New Perspectives

      Terry McNulty, Britt MacKinnon, Phillip Mackey

      Abstract

      In 1998, Terry McNulty presented a paper surveying 41 metallurgical and chemical processing plant case histories, identifying dominant causes of success and failure (McNulty T (1998) Innovative technology: its development and commercialization. In: Kuhn M (ed) Managing innovation in the minerals industry. SME: 1–14.; McNulty in Min Eng 50:50–55, 1998;). Available data yielded four curves portraying achievement rates of design capacity for projects, from successful to unsuccessful. Identifiable characteristics were tabulated, establishing guidelines for project planning or prioritization of projects competing for capital. Updates were presented in 2004, 2014, and 2024. The interpretations of success and failure have remained unchanged, i.e., quality of underlying information, development of process design criteria, experience and commitment of the project owner, and avoidance of fast-track schedules that could suppress careful decision making.

      Some projects appear to defy the original criteria underlying the curves. This contradiction encouraged our reflection:

      • Should the original criteria be updated?
      • Do other factors safely accelerate schedules?

      The original criteria may need updating, but there could be other factors impacting ramp-up performance of projects. While some new projects may belong on an “Accelerated Series 1 Curve”, some may be misrepresented by the “Promoter’s Curve”, which is not empirically based, yet some project owners may be tempted to present it to financing firms, resulting in disappointed stakeholders and shareholders. This paper explores these aspects related to ramp-up performance of projects.

   8. Quality Improvements of Copper Concentrate by Optimizing Operating Conditions of Column Flotation

      Genta Sato

      Abstract

      The quality of copper concentrates is crucial to ensure stable operations in the copper smelting processes where the concentration of refractory elements or compounds in the smelting slag must be controlled within an acceptable level. Al₂O₃ and MgO are typical refractory species contained in copper concentrates, originating from gangue minerals such as albite, and chlorite. High levels of Al₂O₃ and MgO in copper smelting process may precipitate spinel crystals to form an accretion layer on the molten slag/matte interface, leading copper losses into the slag. The levels of Al₂O₃ and MgO in copper concentrate sometimes drastically change even when produced from the same mining facility, especially when there are variations in the ratios of copper mineral such as chalcopyrite (CuFeS₂) and bornite (Cu₅FeS₄). In the present study, laboratory-scale column-flotation equipment was used to develop an operating guideline for cleaner flotation that is independent of the type of copper minerals, in order to maintain or lower the levels of impurities in concentrate. The effects of various column flotation parameters, including froth volume, residence time, and bias, which is defined as the difference between the flow rates of wash water and concentrate water, were investigated. The results showed that Al₂O₃ and MgO bearing gangue minerals were effectively removed from the concentrates by controlling the bias to 0.01–0.015 cm/s while maintaining consistent copper recovery.

   9. Selective Depression of Copper-Activated Pyrite Using Oxalic Acid for Enhanced Chalcopyrite Flotation: Advancing Seabed Resource Beneficiation

      Gde Pandhe Wisnu Suyantara, Akbarshokh Ulmaszoda, Hajime Miki, Doaa Ashraf Eladl, Naoko Okibe

      Abstract

      In seabed resources, pyrite is often closely associated with chalcopyrite, complicating selective separation due to the activation of pyrite surfaces by dissolved copper ions from chalcopyrite. This activation promotes pyrite flotation, making separation difficult and hindering effective beneficiation of seabed resources. This study aims to develop an environmentally friendly flotation process to selectively separate pyrite and chalcopyrite. Oxalic acid is proposed as an eco-friendly reagent to prevent the flotation of copper-activated pyrite, facilitating selective chalcopyrite recovery. Laboratory-scale flotation tests using pure chalcopyrite and pyrite were conducted to evaluate the effectiveness of oxalic acid in depressing copper-activated pyrite. Results showed that oxalic acid selectively inhibited the flotation of pyrite without affecting chalcopyrite under mildly alkaline conditions. Artificial mixtures of chalcopyrite and pyrite were used to confirm the selective action of oxalic acid, and surface analyses with infrared (IR) and X-ray photoelectron spectroscopy (XPS) revealed that oxalic acid reacts with copper ions to form copper oxalate, preventing copper adsorption on pyrite surfaces. This reduces pyrite activation, blocking xanthate collector adsorption and promoting chalcopyrite selectivity. These findings lay the groundwork for advancing a sustainable flotation process for seabed resource beneficiation.

   10. Magnetic Separation of Arsenopyrite Through Cementation with Zinc and Cobalt

       Byunghun Go, Ho- Seok Jeon, Dakyeong Baek, Kyounkeun Yoo

       Abstract

       When exposed to air and water, arsenopyrite in tailings can oxidize, leading to a drop in pH and the release of harmful ions like Fe³⁺ and SO₄²⁻. This process can leach arsenic into the environment, which is a toxic element posing significant risks to both biodiversity and human health. We investigated a more effective approach: using cobalt cementation to eliminate particulate arsenopyrite. In our study, we added zinc powder to a solution containing Co₂⁺ and arsenopyrite. The zinc oxidizes, releasing electrons that flow through the arsenopyrite, reducing Co₂⁺ and depositing cobalt onto the arsenopyrite particles. This cobalt-coated arsenopyrite can then be recovered using magnetic separation. We conducted an experiment using arsenopyrite particles of three different size fractions: + 200 mesh, −200 + 352 mesh and −325 mesh. The removal rates we observed were 22.8, 81.19%, and an impressive 98.5%, respectively, indicating that we achieved over 98% removal for particles smaller than –325 mesh. Additionally, we explored how varying the amounts of arsenopyrite and zinc, cobalt concentration, pH, temperature, and stirring speed affected the results. Our findings suggest that cobalt cementation followed by magnetic separation is a viable and effective method for removing particulate arsenopyrite from tailings, contributing to better environmental management.

   11. Investigation of Flotation Conditions to Separate Arsenic-Bearing Copper Minerals from Copper Concentrate Using Di-n-octyl Sulfide Collector

       Tatsuhiro Ono, S. Magwaneng Refilwe, Shuta Kunihiro, Taisuke Sakakibara, Taro Kamiya, Kazuya Sunada

       Abstract

       In recent years, an increase in the arsenic grade within the copper concentrate has been observed. Arsenic is a common penalty element in the copper mining industry due to the environmental risks associated with its emission in copper smelting. Arsenic is commonly found in association with copper sulfide minerals, particularly in arsenic-bearing copper minerals such as enargite (Cu₃AsS₄) and tennantite ((Cu, Fe, Zn)₁₂(Sb, As)₄S₁₃). In this study, we investigated the potential of Di-n-octyl sulfide (C₁₆H₃₄S, DOS), a component of thioether (R₁-S-R₂) compound, as a selective collector for the flotation of arsenic-bearing copper minerals from copper sulfide minerals. Flotation tests were conducted to evaluate the effect of various conditions, including collector and depressant dosage on the selective separation of arsenic-bearing copper minerals from arsenic contained copper concentrate. The batch flotation test results indicated that the optimal condition for maximum separation efficiency between arsenic-bearing copper minerals and non-arsenic copper minerals was 50.3%. Moreover, the best test result in the rougher and cleaner flotation showed that 90% of arsenic-bearing copper minerals were removed from copper concentrate and arsenic grade was reduced from the initial 1.30 to 0.20%.

   12. The Devil is in the Detail

       David Way, Ryan Bracey, Lyndon Ryan

       Abstract

       Progressing process plant projects from studies to construction and operations requires process design work, preliminary engineering and metallurgical studies to prove up an economic flowsheet and plant layout. This work has a reliance on basic sampling, ore characterisation, and metallurgical testing to a standard that supports sound decision making. Often overlooked and underappreciated is the role of collaboration and multidiscipline approach employing best practices and attention to detail play to maximise the economic extraction of metal. This paper will present examples of sampling practises often observed for copper development projects and compare these against sampling practises considered the best, with supporting evidence. Some of the benefits and pitfalls of domaining practises and tests used for comminution and flotation characterisation will be discussed for a selection of copper case studies. Copper projects developed by Sedgman using these best practises have demonstrated a substantial uplift in NPV by domaining of ores by different comminution and flotation characteristics. The details of one such project will be presented that yielded a 27% increase in the size of the resource and 29% increase in project scale. The domaining also resulted in significant changes to the comminution and flotation circuit design, maximising the economic extraction of metal. A second case study details the importance of comminution and flotation sampling in combination with geospatial considerations. These considerations enabled a new operating schedule to be proposed which resulted in a 34% uplift in copper production over the first 4 years of the project, significantly increasing the overall project value. The case studies presented demonstrate the importance of best practise with respect to sampling, ore characterisation, domaining and metallurgical testing to support the design basis, and technical and economic viability of copper development projects.

   13. A Primary Study on Predicting Flotation Outcomes Based on Particles Group Characteristics Using MLA Data and Machine Learning

       Takeshi Shibuya, Seyong Park, Shun Ichige, Taiga Sato, Taisuke Sakakibara, Tatsuhiro Ono, Taro Kamiya, Kazuya Sunada

       Abstract

       This study aims to develop a support tool to beneficiation process for mine development projects by leveraging machine learning on features of mineral particles obtained with electron microscopy and X-ray spectroscopy from a minimal quantity of ore samples. In this paper, a methodology to construct a predictive model for flotation outcomes, including grade and recovery rate under the same ore and flotation condition is proposed as a primary study. In the experiment, copper ore feed subjected to various grinding conditions, along with the concentrates and tailings obtained from flotation tests, were used. Training data for particle features were obtained using Mineral Liberation Analyzer and a predictive model was subsequently constructed using machine learning and evaluated for prediction accuracy. As a result, the predictions by the method were closer to the true values for test data under grinding conditions not included in the training dataset. This study contributes to solving the challenge of determining effective operating conditions with a limited number of preliminary tests.

   14. Optimizing Eriez HydroFloat™ Size Selection for a Coarse Particle Flotation Plant

       S. Ali, S. Abbasi-Garravand, D. Frost, C. Helfer, J. Concha, E. Wasmund

       Abstract

       As worldwide copper demand rises to facilitate the shift to electrification, mining companies are exploring innovative methods to boost mill throughput and recovery efficiency. Eriez developed the HydroFloat™ Separator, a fluidized teeter bed flotation technology to float coarse particles that are inefficiently recovered in conventional flotation. The largest HydroFloat in operation is 5.0 m in diameter. Copper porphyry concentrators often have large design throughputs of over a 100,000 tonnes of ore per day, requiring the installation of several HydroFloats. The opportunity exists to simplify Coarse Particle Flotation (CPF) flowsheets by using fewer, larger diameter units for a given throughput. Furthermore, current industry interest is geared towards retrofitting CPF to brownfield sites, requiring consideration of layout and infrastructure constraints. Eriez understands the importance of addressing both of these realities in developing the next generation of larger HydroFloats. This paper examines the impact of utilizing larger HydroFloats on the design of a conceptual 135 ktpd CPF plant, ranging from a base case with 3.3 m diameter units up to conceptual 9.0 m units. Process design, equipment selection, layout, Capex and Opex are evaluated for each case. The key criteria for HydroFloat size selection in large copper projects are identified and the optimum HydroFloat size for the 135 ktpd plant is determined.

   15. Arsenic Removal and Stabilization from Enargite, Arsenopyrite and Tennantite Copper/Gold Concentrates

       Olivier Sanfaçon, Joey Isabelle, Jean-Philippe Mai

       Abstract

       Due to increasing scarcity of clean copper ore, a sustainable and economical approach to treat arsenic (As)-contaminated concentrates derived from the base and precious metal mining industry has been developed by Dundee Sustainable Technologies (DST). In the scope of this study, different copper concentrates were partially roasted for the purpose of As removal. The arsenical by-product generated in the proposed flowsheet (As₂O₃) is directly amenable to Dundee Sustainable Technologie’s GlassLock Process™, which stabilizes As using vitrification. Heat treatment trials, targeting a final As concentration below 0.3%wt, were performed at the laboratory scale on three concentrates: enargite (6.2%wt As), arsenopyrite (12.8%wt As) and tennantite (5.7%wt As). The equipment deployed consisted of a Lindberg tube furnace for which the sealed glass tube was linked to an ABB gas analyzer. This also permitted the recovery of the volatilized by-product. Conditions for the partial roasting tests conducted were the following: O_2(g) depleted medium / injection of SO_2(g), 630–700 °C, 40–60 min at operating temperature, under low vacuum. Under these conditions, final As content was between 18 and 3,300 mg/kg corresponding to a removal efficiency ranging from 95.8 to 99.9% for the 3 materials tested. The tennantite calcined residue and recovered As sulfide by-product characterization is presented in this paper. In the proposed approach, the collected As sulfide product is oxidized to As trioxide under heat treatment, generating an ideal feed for DST’s vitrification process. DST’s conceptual flowsheet for an industrial scale application for the removal and stabilization of As from copper/gold concentrate using a fluidized bed reactor is also discussed. The work conducted in this study presents the clear benefits of combining pyrolysis with vitrification, both from an economic and environmental standpoint by reducing or negating market penalty / residual waste management costs associated with As contamination in the concentrates. Long-term environmental, social and governance liability risk in mine closure contexts is also significantly reduced. Furthermore, improved metal recoveries during subsequent hydrometallurgical operations are expected due to refractory sulfides partial thermal decomposition, as well as lower footprint due to selective mass loss and metal grade increase.

   16. Modernization of Molybdenum Flotation: A Case Study with Rio Tinto Kennecott Copper

       Cory Smith, Cameron Strauss, David Hatton, Tuhin Banerjee

       Abstract

       The optimization of mineral processing circuits plays a pivotal role in improving the efficiency and profitability of operations. This paper presents a case study illustrating the collaboration between Rio Tinto Kennecott Copper (RTKC) and Woodgrove Technologies to enhance the molybdenum plant operations at the Kennecott facility in Salt Lake City, Utah. The project’s success was achieved through a comprehensive approach involving pilot plant (PP) testing and advanced modeling. Woodgrove conducted an extensive series of approximately 100 PP tests to gain an in-depth understanding of the molybdenum flotation circuit’s behavior and performance. This rigorous testing provided valuable insights that guided the subsequent phases of the project. Advanced modeling techniques were employed to demonstrate the advantages of replacing legacy flotation equipment with Woodgrove’s Direct Flotation Reactor (DFR ®). These reactors offer improved efficiency and performance, leading to enhanced product quality and reduced operational costs. The modeling efforts provided a tangible basis for RTKC to carry out design engineering for retrofitting of the existing conventional flotation cells with DFRs. The case study highlights the significance of data-driven decision-making in modernizing mineral processing facilities. By leveraging PP testing and advanced modeling, Woodgrove and RTKC successfully optimized the molybdenum flotation circuit design to improve efficiency and operational excellence.

   17. On the Use of Radiotracers in the Mining Industry

       Juan Carlos Salas, Francisco Diaz

       Abstract

       The use of radiotracer techniques is well-established as a valuable tool for troubleshooting and process optimization in various industries that rely on solution or pulp distribution systems. Industrial radiotracers have proven to be highly useful for examining and verifying the condition of several mineral processing systems in areas such as comminution, flotation, and leaching, as well as in the characterization of water management systems. One of the most well-known applications is the determination of residence time distribution through the online monitoring of a radioactive tracer. This technique allows for the assessment of several characteristics of the reactor’s performance using a combination of modeling and analysis of the measured variables. Additionally, the technique can be used for characterizing flow distributions in solution or pulp systems, calibrating flow measurement devices in a non-invasive manner, and characterizing flow patterns in metallurgical reactors. In this article, several applications of radioactive tracers in large-scale industrial mining operations, both in mineral processing and hydrometallurgical processing, are described, underscoring the versatility and necessity of tracer techniques in mining industries, highlighting their role in optimizing processes, ensuring safety, and improving overall performance.

   18. Application of Eriez SlamJet™ Sparger Columns in Mirador Mine Cu-Au–Ag Ore Flotation

       Dong Li, Maoming Fan, Xianren Dai, Aichun Liu, Shinan Li

       Abstract

       Mirador copper-gold-silver mine is a large-scale open-pit mining operation located in southern Ecuador, containing 3.2 Mt of copper, 3.4 Moz of gold, and 27.1 Moz of silver. After extension, the ore production will increase from the current rate of 20 Mt/year to 26.2 Mt/year. Four Ø5 m × 12 m Eriez flotation columns with SlamJet™ Spargers went into production in 2019. The superior cleaner metallurgical performance of column cells achieved are largely attributed to Eriez SlamJet™, which has a unique geometry for the excellent gas sparging systems and to readily accommodating the use of froth washing systems. This paper presents findings from a study on the effects of various parameters on the full-scale column flotation performance. The effects of feed particle size, solids content, froth zone depth, sparger air rate, and wash water rate on the commercial scale column flotation concentrate grade, enrichment ratio, flotation yield and recovery will be discussed. Under optimized conditions, a concentrate of approximately 25% Cu was achieved at over 92% flotation recovery. It was found in the Mirador plant that the combination of fine and ultrafine bubbles produced by specially designed and operated Eriez SlamJet™ Spargers can enhance minus 5 µm ultrafine particles flotation recovery. In this paper, a fundamental study was also performed to improve flotation selectivity of the minus 5 µm ultrafine particle size fraction.

   19. Efficient Copper Extraction by Combined Method of Additive Roasting and Acid Leaching from High-Sulfide Copper Concentrate

       Bekhzod Gayratov, Labone L. Godirilwe, Sanghee Jeon, Atsushi Shibayama

       Abstract

       The mineral processing industry faces new challenges due to decreasing ore grades and increasing copper ore complexity. The process of extracting copper from copper sulfide ore is extremely intricate and specifically chalcopyrite, the most common copper-bearing mineral, needs a strong oxidizing reagent to rupture its resistant structure. Roasting with additives is an effective pre-treatment for chalcopyrite as it transforms the mineral into a more leachable form, overcoming the limitations of direct leaching, which is hindered by passivating layers that form on the mineral surface, reducing copper recovery. Therefore, this research focuses on recovering copper from flotation concentrate using combined additive roasting and leaching methods. Experiments were conducted using a copper sulfide ore sample containing chalcopyrite (CuFeS₂) as the main Cu-bearing mineral and gangue minerals such as quartz (SiO₂), pyrite (FeS₂) and feldspar (К[AlSi₃O₈]). X-ray fluorescence and microwave plasma atomic emission spectroscopy showed 0.94% Cu and 4.14% Fe. Optimal flotation conditions (7 min, 100 g/t PAX, 1.5 L/min air, pH 10, −75 µm particle size) yielded a copper concentrate with 5.6% Cu and 93.25% recovery which was used as a feed sample in this study. Roasting of copper concentrate with additives like KCl and NaOH at different ratios, roasting temperature and time was performed and atmospheric leaching parameters such as sulfuric acid concentration, temperature, time and pulp density were examined. Results showed that roasting at 600 °C resulted in Cu dissolutions of 94% with KCl (1:0.1) for 2 h and 93% with NaOH (1:0.05) for 1 h in 0.1 M sulfuric acid solution at 25° C with iron dissolution staying below 10% by atmospheric leaching. As a result, copper concentrate roasting with NaOH proved to be beneficial, providing faster reaction kinetics, improved environmental safety and greater economic efficiency.

   20. Applying an Atomic Force Microscopy to Study the In-Situ Adsorption of Collectors on Copper Oxide Minerals

       Jinhong Zhang

       Abstract

       The adsorption of collectors on mineral surface is critical for a successful flotation of copper oxide minerals. In the present study, atomic force microscopy (AFM) has been applied to study the in situ adsorption of hydroxamic collectors, i.e., octanohydroxamic acid (OHA), on copper oxide minerals, such as malachite, in aqueous solutions. AFM images show that hydroxamic collectors adsorb strongly on malachite mainly in the form of insoluble copper hydroxamate complex. Increasing the collectors’ concentration and the adsorption time both increase the adsorption of hydroxamic collectors on malachite. The test results as obtained with the attenuated total reflectance–Fourier transform infrared spectrometry show that the collector adsorbs onto copper oxide minerals, with strong absorbance spectra being detected. These results confirm those as obtained with an AFM. Test results also show that a hydroxamic acid collector has a moderate collectivity for the flotation of copper oxide minerals. The findings also show that AFM image analysis is a powerful tool for the study of the collectors’ adsorption on copper mineral surface, and therefore the flotation of copper minerals.

   21. Molten Sulfide Electrolysis for Processing Chalcopyrite and Pyrite

       Extended Abstract Katrin Daehn, Natalie Chapman, Antoine Allanore

       Abstract

       Technologies to decouple metal production from CO₂ emissions while maintaining high productivity and adapting to increasingly complex ore and waste feedstocks are urgently needed. Molten sulfide electrolysis (MSE) uses sulfide chemistry to substitute for oxides for reduction, eliminating the need for carbon and consequent greenhouse gas (GHG) emissions. A supporting electrolyte with sufficient ionic conductivity dissolves sulfide feedstocks at high concentrations, depositing metal at the cathode while sulfur gas is generated at the graphite anode. Previous demonstration of this process in a 100A reactor showed the sequential deposition of liquid iron and copper from chalcopyrite (CuFeS₂). More recent work shows the applicability of MSE to electrolytically decompose pyrite (FeS) to produce cast iron with faradaic efficiency of >90% at current densities of >1.5 A/cm², demonstrating a viable route for ironmaking. The electrochemical properties of the novel electrolyte at the heart of the process are in the early stages of investigation. Initial measurements for total and electronic conductivity will be presented to begin shedding light on the mechanisms underlying the process and the implications of mixed conductivity.

   22. Tailings Dewatering: Enabling High-Tonnage Solutions

       Kaci Jenkins

       Abstract

       Management of tailings storage facilities (TSFs) is a top risk in the mining industry. Water stored within TSFs can cause failures (overtopping, liquefaction) or make a slope failure worse by eroding the embankment. Failures of conventional TSFs have heightened awareness of these hazards within mining communities and regulatory oversight groups. The industry is exploring ways to improve tailings management practices by reducing water consumption, limiting or eliminating water sent to the facility, improving environmental performance, and limiting the facility footprint. While tailings dewatering has been successfully implemented up to 45,000 metric tonnes, more work is needed to implement these solutions at the tonnages required by copper mines, where daily tailings generation can be upwards of 100,000 metric tonnes. The size of this challenge is expected to increase as copper demand increases and ore grades decline. Annual tailings production from global copper operations in 2022 was approximately 3.8 billion metric tonnes and is estimated to climb to 6.8 billion metric tonnes by 2042. This paper discusses how Rio Tinto is tackling this industry challenge. First, BHP and Rio Tinto have established a consortium with the goal of accelerating development of dewatering technologies and successfully implementing these technologies at large scale (upwards of 30,000 tons per day). Rio Tinto also constructed a tailings technology test bed in 2023 that is currently being used to gain insight into how process variability impacts tailings dewatering. Both scopes of work will be discussed.

   23. Coarse Particle Recovery by Jig Flotation

       Mohit Gupta, Jack Leland, Ashwin Srinivasan, Roe-Hoan Yoon

       Abstract

       Coarse particles are difficult to float as they are readily detached from air bubbles due to the turbulence in the pulp phase of a flotation cell. Many investigators showed indeed that coarse particle recovery can be improved by minimizing the turbulence. In the present work, coarse particle flotation was improved using a jig flotation cell, in which bubble-particle aggregates move upward during the pulsion cycle in which bubble-particle aggregates move by acceleration with no drag force and hence low probability of detachment. Furthermore, the jig motion forms a froth phase, in which less hydrophobic particles drop off to obtain high-grade concentrates. Also, one can feed a copper ore without desliming. Experimental results obtained in the present work show that jig flotation improves both the coarse and fine particle flotation. Some of the tests were conducted using Super Collectors that can increase contact angles above 150° to minimize detachment to increase the upper particle size limit.

   24. Geometallurgy Applied to Copper Projects to Optimize Beneficiation Processes

       D. Connelly

       Abstract

       A common question raised by Mine Managers is why do we need geometallurgy, what are the costs and the benefits? Geometallurgy is an interdisciplinary field that integrates geology, mining and metallurgy. Its purpose is to create predictive models for metallurgical behaviour before the ore is extracted. The aim is to fundamentally improve understanding of resource economics across the project. Geometallurgy is a proven strategy for effective ore characterization and improved prediction of process variability and can be used to enhance economics and reduce risk. Geometallurgy can optimize the life of a project. Implementing geometallurgy requires planning and developing a database and inputting this into ore block models that display the distribution of key metallurgical parameters throughout the orebody that supports metallurgical process modelling and adds value to the planning and optimization process. A geometallurgical modelling approach can directly reduce the risks in production stages, such as meeting the production targets. Geometallurgy acts on both consequences and likelihood axes in reducing the risk. This paper will delve into some important case studies where geometallurgy has made breakthroughs in mine function and continues to be developed today, fostering innovation and productivity.

   25. Options for Large Low Grade Copper Projects

       D. Connelly

       Abstract

       Previous work that was conducted on a large low-grade Copper Project suggested that a conventional method featuring a crush-grind-float and sale of copper concentrate method was not economically feasible due to the hardness and low grade of the copper ore, which would require a significant amount of energy for grinding and therefore a high capital and operating cost. For large low grade copper projects, the conventional crush-grind-float is not financially viable even at current copper prices. However new technology such as ore sorting, high pressure grinding rolls (HPGR) and coarse particle flotation (CPF) can reduce energy costs significantly, making these resources technically and commercially viable. Energy is usually the largest cost for such projects, so reducing the energy costs to process low grade ores is critical. As an example, CPF can achieve 80% recovery at 500 microns, significantly reducing energy costs. If the main mineralised hosts in the copper deposit are coarse grained the process is more amenable than for fine grained disseminated ores. Similarly, sensor-based ore sorting is a mineral pre-concentration technology in which particles of material are separated based on some physical or chemical property as measured or inferred by a sensor. It is used to upgrade the process feed by identifying and rejecting waste material early in the mining process. Sensor-based ore sorting results in the pre-concentration of valuable materials into a lower gross volume. For disseminated copper ores the results can improve grades dramatically. Heap leaching is another option due to the vast scale of these orebodies and the low-grade nature of the ores. New innovations using catalysed chemistry have changed process options for heap leaching, particularly using HPGR which allows finer crush sizes. Bacterial leaching at 60 centigrade overcomes the passivation of chalcopyrite and pyrite causing the ore to generate acid for leaching. The costs associated with heap leaching compared to a whole ore floatation circuit are considerably lower. In addition, the removal of fines and flotation of a pyrite copper concentrate can be used to feed a roaster to produce acid on site reducing operating costs for the heap leach.

   26. Optimising Scheelite Processing at the Kara Mine, Tasmania: A Case Study of a Novel Flotation Collector and Depressant

       Emmanuel Dogara Musa, Mohammadbagher Fathi, Julie Hunt, Owen Missen, Greg Doherty, Marcus Mollison

       Abstract

       Scheelite (CaWO₄) has emerged as the primary source of tungsten (W), a critical metal with a high economic importance and supply risk. The processing of scheelite-bearing skarn deposits is challenging due to the similar surface properties of scheelite and associated calcium-bearing gangue minerals such as garnet, vesuvianite, calcite and fluorite. This study investigates the potential of a novel anionic collector, Berol 8313, and a depressant, polyaspartic acid (PASP), to enhance the separation efficiency of scheelite from other calcium-bearing minerals. Flotation tests were carried out using plant samples from the Tasmania Mines scheelite processing facility, with varying reagent dosages (collector and depressant: 50–200 g/t) and pH levels (8–11) This study highlights the potential of Berol 8313 and PASP as selective reagents for scheelite processing in skarn deposits, offering an improved approach to tungsten recovery.

   27. Expanding Capacity at the Morenci Copper Concentrate Pressure Leach Plant

       A. Banda, R. D. Frischmuth

       Abstract

       The Morenci copper concentrate leach plant (CLP) was initially commissioned and operated in late 2007, using partial sulfide oxidation and medium-temperature direct electrowinning conditions. The plant was shut down in mid-2008, primarily due to low copper prices. Favorable copper economics and the additional benefit of acid production for heap leach operations justified refurbishment and recommissioning of the plant in May 2015. The recommissioning included assessment and modifications to operate using complete sulfide oxidation, high-temperature conditions (HT). An initial capacity assessment study in 2021 identified an opportunity to increase the CLP capacity from the current operations at 22 t/h (24 st/h) to 36 t/h (40 st/h) without modifying the two autoclaves, known on site as pressure leach vessels (PLV). Additional studies identified significant modifications required for the off-gas circuit and oxygen plant capacity, as well as other less significant modifications throughout the other plant areas. Engineering, procurement and construction management (EPCM) of the Morenci CLP expansion project was initiated in early 2023, with the goal of beginning construction in early 2025 and ramp-up by mid-2025. This paper provides an overview of the Morenci CLP expansion project modifications.

   28. Advancements in Flotation Technology: A Design Perspective

       Y. S. Cho, M. Oliazadeh, L. Guo

       Abstract

       Flotation remains a cornerstone process for the beneficiation of sulfide minerals. Over the past century, advancements in flotation technology have focused on increasing the capacity of flotation cells, with modern designs achieving volumes over 600 m³ compared to just 14 m³ in 1970. Recent innovations, such as the Jameson Cell, StackCell^®, and Direct Flotation Reactor, aim to address key challenges, including enhancing flotation efficiency for fine particles, reducing energy consumption, and minimizing operating costs. While many studies have compared the performance of these technologies, they have often been vendor-driven and primarily focused on operational performance. This paper offers a broader perspective by emphasizing the engineering aspects and cost implications of these emerging flotation technologies. Key considerations include the footprint and layout of sulfide copper flotation plants. A conceptual flotation plant with a capacity of 65,000 tpd copper ore was designed, integrating both conventional tank cells and advanced emerging flotation technologies.

   29. Metallurgical Performance of Industrial Scale Concorde Cell™ in Improving Fines Recovery

       Raghav Dube, Nathalie Kupka, Alejandro Yañez, Antti Rinne

       Abstract

       The Concorde Cell™ is an advanced pneumatic flotation technology designed to improve the recovery of fine to ultrafine particles through the use of supersonic shockwaves and high shear forces. Initially patented by Prof. Jameson in the late 2000s and officially launched on November 4, 2021, this innovative cell produces fine air bubbles with high carrying capacity, enabling enhanced recovery of valuable particles often lost in traditional flotation processes. Its compact design allows for higher throughput per unit, reduced plant footprints, and fewer flotation stages, significantly lowering operational costs for power and water. The development of the Concorde Cell began with prototype creation in 2018, followed by the introduction of demonstrative and production units into mineral processing flowsheets starting in early 2020. This technology has since been successfully applied in processing copper, gold, platinum, and other minerals. This paper examines the metallurgical performance of the Concorde cell, comparing results from laboratory-scale testing to full-scale implementation in major copper concentrators.