Prix du meilleur article de la Section pyrométallurgie des métaux
Le Prix du meilleur article de la Section pyrométallurgie des métaux a été créé pour récompenser le meilleur article publié sur ce sujet dans le Journal de l’ICM, dans le Canadian Metallurgical Quarterly ou des délibérations de la Conférence des métallurgistes de l’année précédente. La Section sélectionne le meilleur article et le sous-comité de remise de prix examine les nominations.
Ce prix n’est pas ouvert aux nominations du public. Le prix est administré par le comité de la section de MetSoc.
2024 lauréats
Solving the Loss of Arc (LOA) Problem and Its Furnace Process Implications at Koniambo Nickel SAS
Jonathan Spring, Piet Swart, Ron Schonewille, Fred Greyling, and Gerrit Liebenberg
Presented at COM 2024, « Extractive Metallurgy from Conception to Operation: Experimentation, Simulation, Pilot, and Ramp-up » Symposium (ID# COM24019)
The two twin-electrode DC furnaces at Koniambo Nickel SAS (KNS) have suffered from a loss of arc (LOA) problem since commissioning. LOA manifests itself by the sudden extinguishing of the electric arc between the electrode tip and slag bath. LOA occurred randomly with no clear correlation to process parameters. Lost power from LOA led to large fluctuations of the power to feed ratio in the furnace. The inability to run at stable high power and frequent stoppages to correct power to feed imbalances were the main barrier to achieving the nominal furnace design production rate. Heuristic process levers were developed to reduce the occurrence of LOA. None showed systematic, reproducible benefits to LOA reduction and the root cause remained unknown. Bench scale tests were run which clearly and reproducibly showed the events leading up to LOA. These events are explained using electromagnetic theory. The LOA problem was solved by reversing the polarity of one electrode which converts the attractive force experienced by the arcs into a repulsive force. Both furnaces were converted to this new configuration by the physical rotation of the rectifier thyristors of one electrode. Following the change, LOA frequency was drastically reduced. Furnace power setpoints above 100 MW are now readily achieved with no need for constant process parameter adjustments. The increased electric stability has led to increased process stability with no negative consequences to furnace integrity.
Kinetic Study in Selection Reduction of Limonitic and Saprolitic Nickel Ore
Bambang Suharno, Fajar Nurjaman, Soesaptri Oediyani, Anton Sapto Handoko, Fathan Bahfie, Abdul Fathir Qaulanhaq, Widi Astuti and Erik Prasetyo
Published in The Canadian Metallurgical Quarterly. Volume 63 – Issue 3
Saprolite and limonite have different behaviour in the carbothermic reduction process due to the differences in their atomic structures. This work investigates the kinetic study of these two different kinds of lateritic nickel ores. Nickel ore, coal, sodium sulfate, and calcium oxide were mixed, then pelletised into 10–15 mm diameters. The pellets were reduced with a non-isothermal condition using a muffle furnace at 950–1150 °C for 5–120 min. The reduced pellets were crushed into less than 74 µm prior to the wet magnetic separation process to obtain concentrates (ferronickel) and tailings (impurities). The result showed that the reduction rate for both lateritic nickel ores increased with the increase of reduction temperature and holding time. The Ginstling-Brouhnstein model was appropriate to describe the diffusion mechanism of the reduction process of limonite and saprolite. The activation energy in the reduction of limonite was lower than in saprolite. It indicated that the iron and nickel in magnesium silicate in saprolite have lower reducibility than the oxide structure in limonite. Modifying basicity in nickel laterite with CaO addition could also reduce the activation energy.
Lauréat 2023
H2 injection in molten metal
Author: Torben Eden, Aurubis
Presented at COM 2022, « Deep Decarbonization Pathways for Pyrometallurgical Processes: Opportunities & Challenges » symposium
Résumé
The deoxidation of copper or “poling” is the final step in the pyrometallurgical process of primary and secondary copper extraction. The deoxidation generates CO2 since gaseous and liquid hydrocarbons (natural gas) are the common choice for reducing agents. Previous energy and cost saving measures increased the efficiency of the process, but the inherent production of CO2 cannot be avoided. The use of hydrogen as a reductant may decarbonise a core process of copper production, which is a desirable target for the metal industry in general and Aurubis in particular.
The primary smelter in Hamburg runs two anode furnaces with a capacity of 270 t per batch each. From September to December 2021, the anode furnaces were provisionally supplied with hydrogen and 14 batches were poled using hydrogen. These experiments were designed to determine in full scale operational tests the properties of the poling with hydrogen in terms of efficiency and process control.
The average efficiency of poling with hydrogen was higher than poling with natural gas. The adjustment of the volume flows and the temperature control of the process was always controllable. The end point of the poling with hydrogen could be determined similarly to the poling with natural gas based on the temperature curve.
The tests showed the importance of nitrogen addition for stable jetting conditions where clogging of the tuyeres was a phenomenon observed when pure hydrogen was used. An important observation from the tests was that the efficiency of the reduction was not affected by the addition of nitrogen.
This paper will discuss in detail and share the learnings of full-scale polling tests in the Hamburg anode furnace and discuss requirements for its introduction into the daily production.
Lauréat 2022
Recycling Ferronickel Concentrates as an Iron Source to Extract Nickel from Nickel Sulphide Concentrates
Fanmao Wang, Sam Marcuson, Mansoor Barati and Leili Tafaghodi
Présenté à COM 2021-WALSIM symposium
Résumé
The conventional nickel extraction from sulphide nickel ore consists of smelting and refining, producing high purity metallic nickel products. The limit of the traditional extraction process is the significant cost of SO2 abatement, disposal of by-products (e.g., slags), and complex refining treatment. With the interest of reducing SO2 emissions and simplifying the extraction process, the authors investigated a solid-state (800 oC) thermal treatment of nickel sulphide concentrates in the presence of metallic iron under a neutral atmosphere. The results showed that approximately 97% of Ni was extracted into ferronickel (FeNi) particles with d80 = 45 µm. Recycling these FeNi particles as an iron source yielded new FeNi precipitations in the sulphide matrix with d80 = 20 µm. The Ni concentration in the resulting sulphide phase was in the range of 1–3 wt%. Optimization is required to use the recycled FeNi particles as seeds to increase the size of newly precipitated alloy particles.
Lauréat 2021
Trace Element Distributions Between Matte and Slag in Direct Nickel Matte Smelting
Sukhomlinov, D., Klemettinen, L., Virtanen, O., Lahaye, Y., Latostenmaa, P., Jokilaakso, A., & Taskinen, P.
(2020) Canadian Metallurgical Quarterly, 59(1), 67-77.
Résumé
Abstract: The behaviour of trace elements in the nickel matte smelting was studied at 1673 K (1400°C) by equilibration-quenching techniques followed by direct phase analyses using electron probe X-ray microanalysis and laser ablation inductively coupled plasma-mass spectrometry. The matte-slag samples at silica saturation were equilibrated with SO2-CO-CO2-Ar mixtures of fixed pSO2, pS2 and pO2 in order to obtain a pre-determined oxidation degree for the sulphide matte, and thus to
generate a targeted iron concentration of the nickel-copper–iron sulphide matte (Ni: Cu = 5, w/w), depending on the slag chemistry. The slag composition was varied from 0 to 2 wt-% K2O and 0–10 wt-% MgO in silica saturation. The studied trace elements were Co, Ge, Pb, Se and Sn, but also the matte-to-slag distributions of the slag forming fluxing components Mg (MgO) and Si (SiO2) were determined experimentally. Selenium was the only trace element studied which strongly enriched in the low-iron nickel mattes, and the deportment became larger when the sulphide matte depleted with iron. All the other trace elements behaved in the opposite way.
