Ari Jokilaakso

• PhD
• Professor (Associate) at Aalto University

Recycling of lithium-ion batteries has become essential to meet the demand for critical raw materials, especially lithium (Li) and cobalt (Co). Selective sulfation roasting followed by water leaching has been shown to be a promising route for recycling. However, it is very challenging to achieve high metal recovery efficiencies consistently with di...

Waste lithium-ion batteries (LIBs) are important secondary sources of valuable materials, including Critical Raw Materials (CRMs) like lithium, cobalt, manganese, and graphite, as defined by the European Union (EU). LIBs also contain nickel and copper, classified as Strategic Raw Materials by the EU since 2023. Significant efforts have been made to...

The suspension oxidation of nickel sulfide concentrates in flash smelting conditions was studied using a laboratory-scale laminar flow furnace. The effects of temperature (800-1100 °C ) and oxygen concentration (40-85 vol%) in the process gas were investigated. The surface morphology and mineralogical compositions of samples were examined using sca...

Controlled recycling of battery scrap to recover valuable metals has become essential nowadays not only to fulfill the demand for critical raw materials but also to mitigate the environmental impacts due to the possible release of toxic chemicals and heavy metals from this waste fraction. In the current research, selective sulfation roasting combin...

The Na2O‐SiO2‐TiO2 system is important for the glass, ceramic, and metallurgical industries. Its features provide information on the composition and melting temperature to be utilized during the production of glass and ceramic and during the processing of TiO2‐bearing material in the metallurgical industry. The liquidus temperatures between 900 and...

With the purpose of recovering the metal values, in this study the copper slag was reduced by coke and biochar at 1250 °C in an argon gas atmosphere using the isothermal reduction/drop quenching technique. The phase compositions of metal, matte, and slag were determined using electron probe microanalysis (EPMA). The effects of reduction time and am...

The ignition and oxidation behavior of synthesized sulfur-lean nickel mattes was investigated using a laminar flow furnace simulating the conditions in the flash smelting reaction shaft to explore the ignition and oxidation processes of sulfur-lean electric furnace mattes obtained from slag cleaning. The experiments were conducted at 800-1100 ℃ wit...

Phase equilibria in the CaO–SiO2–CrOx system were experimentally investigated at 1600°C and pO2 of 10⁻¹⁰ to 10⁻¹¹ atm using the high‐temperature isothermal equilibration/drop quenching/electron probe X‐ray microanalysis technique. The constrained isothermal sections of the CaO–SiO2–CrOx system were constructed at 1600°C and pO2 of 10⁻¹⁰ to 10⁻¹¹ at...

The study aims to comprehend the behavior of nitrogen in the argon oxygen decarburization (AOD) process during the production of nitrogen‐alloyed stainless steels, where the precise adjustment of nitrogen content plays a crucial role in enhancing productivity. Furthermore, the objective is to investigate the rate of change in nitrogen content when...

In numerous stainless steels, nitrogen is used as an alloying element to improve mechanical and corrosion properties. The typical nitrogen content is up to 0.5 pct. A common method for alloying is to blow nitrogen gas into an Argon Oxygen Decarburization (AOD) converter. Depending on the steel composition, operating practice, and process conditions...

This study aims at recovering valuable metals from nickel slag by employing pyrometallurgical techniques. A large amount of slag is generated during the nickel matte smelting. Nickel slag contains valuable elements such as copper, nickel, and cobalt, which can be recovered. Disposal of this slag results in loss of resources and may cause pollution...

The flash smelting furnace has previously been simulated using computational fluid dynamics (CFD). A new approach is to combine CFD and the discrete element method (DEM) for more detailed simulations of the different phenomena that occur as copper matte droplets settle through a slag layer. One of the most important phenomena found is the formation...

The flash smelting process is widely used in copper production. In the process, sulfidic feed and flux are oxidized. The heat released in the reactions melts the feed which forms a slag layer through which matte droplets must settle. Understanding the different phenomena affecting the settling is important to minimize losses. Due to the high temper...

Arsenic is a common impurity element in sulfide concentrates. It tends to accumulate in the flue dust of smelting furnace due to the volatility and internal circulation of the flue dust practiced in the smelting-converting process chain. The only outlets for arsenic are anodes and discard slag. Arsenic condensation in dust-free conditions was studi...

Extraction of cobalt from secondary resources has become crucial as cobalt has been identified as strategically important and critical raw material due to high risks in supply chain disruptions. In this work, a novel route has been investigated for selective extraction of cobalt from spent industrial lithium cobalt oxide (LCO)-rich battery scrap. I...

The equilibrium phase relations of the Al2O3-SiO2-CrOx system were experimentally studied at 1600 °C and pO2 of 10-10-10-11 atm. The high-temperature isothermal equilibration experiments were conducted in a vertical tube furnace, followed by drop quenching and direct phase composition analysis using an Electron Probe X-ray Microanalyzer. The singl...

The suitability of a non-fossil reductant in hightemperature treatment of a zinc leach residue was studied in laboratory-scale experiments. The pyrometallurgical experiments carried out at temperatures of 1200−1350 °C consisted of melting the residue under an oxidizing atmosphere to produce an intermediate, desulfurized slag, which was further clea...

The equilibrium phase relations of the MgO–SiO2–CrOx system were investigated at 1600°C in air and at pO2 of 10–10 to 10–11 atm using a high‐temperature isothermal equilibration technique followed by rapid quenching and direct phase composition analyses with electron probe X‐ray microanalysis. Two‐phase equilibria (liquid–cristobalite, liquid–spine...

A previously reported numerical method using the multi-fluid VOF model to simulate an SKS furnace multiphase flow was further verified to provide a good reference for the macroscopic flow field simulation of industrial vessels with similar geometry. Using the verified numerical model, CFD simulation of a full-scale SKS furnace multiphase flow was c...

The extraction of cobalt from secondary resources has become crucial, as cobalt has been identified as a strategically important and critical raw material due to the high risks of supply chain disruptions. In this work, selective sulfation roasting was investigated as a potential recycling strategy to extract cobalt and lithium from an industrial l...

The equilibrium-phase relations between copper mattes and spinel-saturated iron silicate slags were investigated at 1250 °C and pSO2 of 0.25 atm. The experiments were conducted in synthesized spinel crucibles (Fe3O4) in controlled CO-CO2-SO2-Ar gas mixtures using a high-temperature isothermal equilibration/quenching technique. The equilibrium-phase...

The distribution behavior of trace metals between copper matte and spinel-saturated iron silicate slags was investigated at 1250 • C and pSO2 of 0.25 atm at low silica concentrations. The experiments were conducted in magnetite (Fe3O4) spinel crucibles in controlled CO-CO2-SO2-Ar gas mixtures using a high-temperature equilibration-quenching techniq...

The increasing concentrations of metallic Al or Al2O3 in secondary copper resources like electronic wastes motivate research into the slag chemistry of high-Al2O3 iron silicate slags for optimizing the industrial smelting process. In this study, the effect of Al2O3 in slag on the phase equilibria of the FeOx-SiO2-Al2O3 slag system was experimentall...

This study investigated a novel approach of using Al and Al–Mg scrap as heat providers and reductants that do not cause direct carbon-containing emissions in pyrometallurgical copper processing. Aluminum and magnesium are typical elements in metal wastes, such as WEEE, and they oxide easily under copper smelting conditions. In the reduction experim...

As the electrification sector expands rapidly, the demand for metals used in batteries is increasing significantly. New approaches for lithium-ion battery (LIB) recycling have to be investigated and new technologies developed in order to secure the future supply of battery metals (i.e., lithium, cobalt, nickel). In this work, the possibility of int...

About the impact and use of metals as reductants in non-ferrous slag cleaning.

The equilibrium phase relations between metallic copper alloys and magnetite/wüstite-saturated iron silicate slags were investigated at 1200–1300 °C and PO2 of 10⁻¹⁰ to 10−6.5 atm. The experiments involved high-temperature equilibration of samples in a controlled CO–CO2 atmosphere, followed by rapid drop quenching and direct measurement of the phas...

The role of nitrogen varies in different stainless steels from a harmful impurity to a valuable alloying element. Therefore, the strict control of nitrogen content is a very important issue in the steel making process. Better understanding about the thermodynamics of nitrogen solubility is the basis for this control. The aim of this study was to de...

A mathematical modeling approach was used to test different design modifications in a flash smelting settler to reduce the copper losses in slag, which is economically disadvantageous for copper processing using the pyrometallurgical route. The main purpose of this study was to find ways to reduce copper losses in slag by improving the settling and...

The equilibrium phase relations of the MgO-CaO-TiO2 system were investigated at 1500-1600°C in air using the high-temperature isothermal equilibration of samples in platinum crucibles followed by the rapid quenching technique. The phase compositions were analyzed using an electron probe X-ray microanalyzer (EPMA). The isothermal sections at 1500°C...

CFD simulation using a multi-fluid VOF model on scaled-down SKS furnace multiphase flow was conducted, targeting the agitation performance under conditions of different tuyere diameters and bath depths, at a constant total gas volumetric flow rate. The results indicate that an increased bath depth contributes to the lateral movements of the matte a...

There has been a great deal of focus on the optimization of tuyere arrangements in SKS bottom blown copper smelting furnaces since the last decade, as the improved furnace operation efficiency of SKS technology has potential that cannot be ignored. New – x + 0 + x deg tuyere arrangements with 14 tuyeres are proposed in this research paper. Using a...

In this study, industrial lithium-ion battery (LIB) waste was treated by a froth flotation process, which allowed selective separation of electrode particles from metallic-rich fractions containing Cu and Al. In the flotation experiments, recovery rates of ~80 and 98.8% for the cathode active elements (Co, Ni, Mn) and graphite were achieved, respec...

The distribution coefficients of Co, Ni, Ag, Au, Pd, and Fe at low concentrations between liquid copper and molten white metal (low-iron copper matte, 'Cu 2 S') were investigated experimentally as a function of temperature (1250-1350°C) and SO 2 partial pressure (0.01-1 atm). The experimental technique involved samples equilibration at controlled t...

Recycling of waste electrical and electronic equipment (WEEE) is attracting increasing attention, due to the presence of valuable metals and the risk of environmental emissions associated with WEEE disposal. In this study, the distributions of trace elements (Ag, Ni, Co, and Sn) between copper alloy and magnetite/wüstite-saturated iron silicate sla...

The aim of this study was to investigate the oxidation kinetics of copper at low temperatures (60 °C to 100 °C) in air by isothermal thermogravimetric analysis (TGA) and quartz crystal microbalance (QCM). The weight change in thermogravimetric tests showed periodic weight increase and decrease. In thermogravimetric tests the mass of the copper samp...

We investigated the phase relations of the SiO2-MgO-TiO2 system in air at 1500 °C using the high-temperature isothermal equilibration/quenching technique, followed by x-ray diffraction measurements and direct phase analysis using scanning electron microscopy coupled with x-ray energy dispersive spectrometry. One single liquid phase domain, five two...

Article in a Finnish trade journal Materia. Deals with the availability of metals needed in the transition towards electrification of transport and renewable energy production.

Flash smelting and flash converting are mature technologies in copper and nickel sulfide smelting. The sensitivity of operation concerning the furnace design is evident. It is obvious that when two unit operations are carried out in separate spaces in the same furnace, skills related to maintenance of suspension oxidation of fine minerals, fluxing,...

One possible way of recovering metals from spent lithium-ion batteries is to integrate the recycling with already existing metallurgical processes. This study continues our effort on integrating froth flotation and nickel-slag cleaning process for metal recovery from spent batteries (SBs), using anodic graphite as the main reductant. The SBs used i...

Sodium sulfate accumulation in the water system is a common problem in the production of primary metals from sulfide minerals. In flash smelting-flash converting copper smelters, when molten copper matte quenched in industrial water to produce matte granules, Na2SO4 precipitated and entered the system, which had negative influence on the matte conv...

The world of stainless steel production was 52 Mt in 2019, and the annual amount of slags including electric furnace, AOD converter, ladle, and casting tundish, was estimated at 15–17 Mt. Nowadays, only a minor fraction of slags from stainless steel production is utilized and a major part goes to landfilling. These slags contain high-value elements...

The recycling and recovery of precious metals from secondary materials, such as waste-printed circuit boards, are an important area of circular economy research due to the limited existing resources and increasing amount of e-waste produced by the rapid development of technology. In this study, the kinetic behavior of precious metals Au, Ag, Pt, an...

In view of the issues of low efficiency and environmental pollution existing in current antimony production, this work proposes an innovative and cleaner process to extract antimony from stibnite concentrate and co-treat goethite residues. The mechanisms of antimony extraction and zinc, iron, sulfur conservation was thermodynamically and experiment...

This current study addresses the role of copper and aluminum - typical major components of current collector scrap from battery manufacturing plants - in the leaching of pre-treated LiCoO2-rich battery waste concentrate at industrially relevant process conditions (T = 60 °C, [H2SO4] = 2 M, S/L = 200 g/L). An empirical model has been constructed whi...

The combined processing of industrial wastes of titania-bearing slags with coal fly ash is an important part of the circular economy. In the present work, the effect of Al2O3 on the 1400 °C liquidus isotherms of the perovskite, rutile and tridymite primary phase fields in the CaO-SiO2-TiO2-Al2O3 system has been determined by employing a high-temper...

Dissolution and solubility of palladium in iron silicate melts saturated with alumina-iron spinel at 1300°C has been measured using an equilibration-drop quenching technique combined with electron probe microanalysis and laser ablation-inductive coupled plasma-mass spectrometry analysis from polished sections. Composition of the resulting Fe-Pd all...

The emerging bottom blown copper smelting (SKS) technology has attracted growing interest since it came into production. To further reveal the agitation behavior inside the bath and optimize the variable parameters, CFD simulation was conducted on a scaled down SKS furnace model with different tuyere arrangements. The Multi-Fluid VOF model was used...

A potential industrial waste-waste co-treatment process was proposed and verified for the recovery of the valuable metals Co, Ni, and Cu from copper smelting slag by utilizing high temperature SO2 off-gas. Sulfation roasting followed by water leaching under designed thermodynamic conditions was conducted to facilitate the selective formation of Co,...

The distributions of precious metals (gold, silver, platinum, and palladium) between copper matte and silica-saturated FeOx-SiO2 /FeOx-SiO2-Al2O3 /FeOx-SiO2-Al2O3-CaO slags were investigated at 1300 °C and PSO2 = 0.5 atm. The experiments were carried out in silica crucibles under flowing CO-CO2-SO2-Ar gas atmosphere. The concentrations of precious...

The world stainless steel production was 51 Mt in 2018 and the amount of slags including electric furnace, AOD, ladles and casting facilities, was estimated at 15 Mt. Nowadays, only a minor fraction of slags from stainless steel production is utilized and a major part goes to landfilling. These slags contain high-value elements (Cr, Ni, Mo, Ti, V.....

The composition of copper smelting slags is changing due to an increase in secondary raw material utilization, as well as changes in flux and ore compositions. These changes can lead to higher concentrations of basic oxides, such as alumina, lime and magnesia in the slags, which in turn may facilitate the formation of solid phases, such as spinels....

One of the existing industrial routes for processing WEEE is through metallurgical processes embedded in primary and secondary base metals productions, such as through Cu smelting. Developing and designing an optimal smelting process utilizing e-waste is one of the biggest challenges for modern metal industries. Copper smelter and converter slags u...

Arsenic is the most important hazardous trace element in copper concentrates. In order to separate arsenic from the smelting processes, a pyrometallurgical treatment with additives was developed to deal with high-arsenic copper smelter flue dust high in copper sulfate. Under the optimized conditions of mixing 30 wt% pyrite and roasting at 550 °C un...

A promising lead-containing waste recycling method, with sulfur conservation and reductive sulfur-fixing co-smelting process (RSFCS), is proposed. This work investigated the PbSO4 reduction equilibrium composition, phase conversions, and microscopic transformation mechanisms during the RSFCS process at different temperatures, times, and CO-CO2 mixt...

Single particle experiments were carried out in the present study. An industrial copper matte powder, containing 68.04 wt.% Cu, 0.50 wt.% Se and 0.08 wt.% Te was taken as the starting material. Se and Te phase assemblies and distribution behaviors were systematically investigated in the air atmosphere. It was found that Se reported to blister coppe...

In the Selective Crystallization and Phase Separation (SCPS) process, manganese oxide is used as an additive to promote the precipitation of perovskite. However, the influence of manganese oxide on the liquid domain of the perovskite primary phase field is still unclear. In the present work, the liquid-perovskite equilibrium with the addition of 0-...

The global amount of waste electrical and electronic equipment (WEEE) is growing fast. Non-ferrous metals represent a large portion of this waste, and they can be potentially recovered via black copper smelting. Alumina and magnesia, originating from the e-waste or fluxes, can be present in the feed of a secondary copper smelter in varying concentr...

Cobalt is a critical, high-value metal used extensively in batteries and other sustainable technologies. To secure its supply in future, it is utmost important to recover cobalt efficiently from industrial wastes and recycled End-of-Life batteries. This study aims at finding ways to improve the reduction of cobalt as well as valuable metals nickel...

SYMMET – Symbiosis of metals production and nature – was aimed at finding ways to minimize waste materials or residues forma- tion in metallurgical processes, and wanted to establish how to best utilize secondary raw materials in existing metallurgical processes. It also wanted to promote the creation of research-based innova- tions and new bus...

Final report of the SYMMET project funded by Business Finland.

Feeding Waste Printed Circuit Boards (WPCBs) into existing pyrometallurgical processes is developing as an easy-to-adapt and efficient way to recycle them. To fulfill sustainability and circular economy targets, kinetics and distributions are the key factors when recovering metals and trace elements from WPCBs. We investigated the reaction mechanis...

Link to the article: https://authors.elsevier.com/c/1bux43IWkc0MrT Alumina is a common substance deporting in copper smelting slags when various secondary copper fractions, e.g. e-scrap or WEEE, are used as feedstock as such or along with primary sulphide concentrates. Properties of iron-silicate slags at high alumina concentrations, in the iron-a...

Bath smelting and converting technologies for copper production have been improved, resulting in higher production efficiency and less polluting emissions. Reported studies on experimental and computational modeling approaches are reviewed in this paper, focusing on adjustable variables and flow details, for a thorough understanding of the complex...

Due to the importance of the physicochemical properties of slag in the recovery of low-titanium ores and by-products, the equilibrium phase relationships of the CaO-MgO-Al 2 O 3-SiO 2-TiO 2 system were experimentally determined using a high-temperature equilibration and quenching method at 1300°C and 1400°C. The equilibrium information was obtained...

The smelting technology and flue dust treatment have an influence on the physical and chemical characteristics of flue dusts collected in copper smelting. We characterized flue dusts from a Bottom-Blowing Bath Smelting (BBS) process and from a Flash Smelting (FS) process by determining their comprehensive physical, chemical, and mineralogical chara...

Experimental study on the phase equilibria between copper matte with silica-saturated iron silicate slags was conducted at 1300 °C and PSO 2 = 0.5 atm. The high-temperature isothermal equilibration in silica crucibles under controlled flowing CO-CO2-SO2-Ar was followed by quenching in an ice-water mixture and direct phase composition analyses by an...

Recycling metals from secondary materials and more complex ores has recently been attracting more attention, creating a need for more precise separation methods of different elements. This study proposed a sulfation-roasting method and designed thermodynamic conditions to selectively facilitate the formation of copper sulfate while separating iron...

With the aim of investigating deportments of precious metals in pyrometallurgical processing of waste electrical and electronic equipment, the distributions of selected precious metals (gold, silver, platinum, and palladium) between copper matte and three different silica-saturated slags (pure FeOx-SiO2 , FeOx-SiO2-Al2O3, and FeOx-SiO2-Al2O3-CaO sl...

The effects of the amphoteric and basic oxides alumina and lime on the phase equilibria of copper matte and silica-saturated slags were investigated at 1300°C and P SO 2 = 0.1 atm in a controlled CO-CO 2-SO 2-Ar gas atmosphere using a high-temperature isothermal equilibration technique followed by rapid quenching. The equilibrium phase compositions...

The amount of copper flash smelting slag has increased during the recent years along with an increasing slag-to-metal ratio. During slag tapping, some copper sulfide is mechanically entrained. As a result, it is necessary to recover copper matte from the slag by suitable methods. At present, the most common way is slow, controlled cooling in a tran...

The equilibrium phase relations and liquidus contours for the TiOx-containing oxide system in reducing atmospheres are of importance in understanding the smelting process of Ti-containing resources. Equilibrium - quenching experiments were conducted at 1400 °C for the CaO–SiO2-TiOx system at oxygen partial pressure of 10⁻¹⁰ atm controlled by a CO/C...

The equilibrium phase relations of the CaO–SiO2–TiO2–Al2O3–MgO system were investigated experimentally in air at 1250–1400 °C using a high-temperature equilibration/quenching technique, followed by direct phase analysis by scanning electron microscopy equipped with X-ray energy dispersive spectroscopy. The equilibrium solid phases of silica, rutile...

Since the current volumes of collected end-of-life lithium ion batteries (LIBs) are low, one option to increase the feasibility of their recycling is to feed them to existing metals production processes. This work presents a novel approach to integrate froth flotation as a mechanical treatment to optimize the recovery of valuable metals from LIB sc...

Innovative recycling routes are needed to fulfill the increasing demand for battery raw materials to ensure sufficiency in the future. The integration of battery scrap recycling and nickel slag cleaning by reduction with methane was experimentally researched for the first time in this study. Industrial nickel slag from the direct Outotec nickel fla...

Phase equilibrium relations for the CaO–SiO2–TiO2-10 wt%Al2O3 system were studied at 1300 °C and 1400 °C by a high temperature equilibration and quenching method, with the purpose of extending the equilibrium phase information for the TiO2-containing slag systems. Equilibrium phase assemblies and phase compositions were analyzed by Scanning Electro...

This work proposes a novel environmentally-friendly, low temperature phase-conversion method for antimony extraction and studies its experimental application and feasibility in pyrite cinder waste co-treatment. The detailed phase transformations and microstructural evolution mechanisms during antimony extraction and sulfur fixation process were inv...

Although Ag-Au alloys are vital for many industries and technological applications, thermodynamic properties data of Ag-Au solid solution are very limited, especially at low temperatures. In the present investigation, activities of silver were directly measured between 550 and 700 K by a solid electromotive force (EMF) method and AgI as the pure io...

Computational methods have become reliable tools in many disciplines for research and industrial design. There are, however, an ever-increasing number of details waiting to be included in the models and software, including, e.g., chemical reactions and many physical phenomena, such as particle and droplet behavior and their interactions. The domina...

Due to the importance of the physicochemical properties of slag in the recovery of low-titanium ores and by-products, the equilibrium phase relationships of the CaO-MgO-Al2O3-SiO2-TiO2 system were experimentally determined using a high-temperature equilibration and quenching method at 1300°C and 1400°C. The equilibrium information was obtained by s...

Experimental data of solid-liquid phase equilibria in the K2O-CaO-SiO2 systems vital for many technologies and industrial applications are very limited and even not available at some primary phase fields. In the present study, by using Equilibration-Quenching-Phase compositional analysis (EPMA/EDS) method, liquidus compositions in equilibrium with...