Mineral chemistry and phase equilibrium constraints on the origin of accretions formed during copper flash smelting

Fernández-Caliani, Juan Carlos; Moreno‐Ventas, I.; Bacedoni, María; Ríos, Guillermo

doi:10.19150/mmp.7247

Cited by 5 publications

(6 citation statements)

References 7 publications

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“…This clearly infers the formation of delafossite from two different mechanisms (see below) and further constrains the exsolution process. This finding is in contrast with ideas that there is no solid solution between the two minerals [21], or the interpretation of the delafossite lamellae in magnetite as the result of a replacement [22].…”

Section: Phase Associations: Exsolutions Versus Solid Solution and Gr...contrasting

confidence: 99%

See 1 more Smart Citation

Copper-Bearing Magnetite and Delafossite in Copper Smelter Slags

Gezzaz,

Ciobanu,

Cook

et al. 2023

Minerals

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The cooling paths and kinetics in the system Cu-Fe-O are investigated by the empirical micro- and nanoscale analysis of slags from the flash furnace smelter at Olympic Dam, South Australia. We aim to constrain the exsolution mechanism of delafossite (Cu1+Fe3+O2) from a spinel solid solution (magnetite, Fe3O4) and understand why cuprospinel (CuFe2O4) is never observed, even though, as a species isostructural with magnetite, it might be expected to form. Flash furnace slags produced in the direct-to-blister copper smelter at Olympic Dam contain four Cu-bearing phases: Cu-bearing magnetite, delafossite, metallic copper, and cuprite. Delafossite coexists with magnetite as rims and lamellar exsolutions, as well as bladed aggregates, associated with cuprite within Si-rich glass. The empirical compositions of magnetite and rim delafossite are (Fe2+6.89Cu2+0.86Co0.13Mg0.15Si0.02)8.05 (Fe3+15.52Al0.41Ti0.01Cr0.01)15.95O32, and (Cu1+0.993Co0.002Mg0.002)0.997(Fe3+0.957Al0.027Ti0.005Si0.004)0.993O2, respectively. The measured Cu content of magnetite represents a combination of a solid solution (~6 mol.% cuprospinel endmember) and exsolved delafossite lamellae. Atomic-resolution high-angle annular dark field scanning transmission electron microscope (HAADF STEM) imaging shows epitaxial relationships between delafossite lamellae and host magnetite. Defects promoting the formation of copper nanoparticles towards the lamellae margins suggest rapid kinetics. Dynamic crystallization under locally induced stress in a supercooled system (glass) is recognized from misorientation lamellae in delafossite formed outside magnetite grains. The observations are concordant with crystallization during the cooling of molten slag from 1300 °C to <1080 °C. Melt separation through an immiscibility gap below the solvus in the system Cu-Fe-O is invoked to form the two distinct delafossite associations: (i) melt-1 from which magnetite + delafossite form; and (ii) melt-2 from which delafossite + cuprite form. Such a path also corroborates the published data explaining the lack of cuprospinel as a discrete phase in the slag. Delafossite rims form on magnetite at a peritectic temperature of ~1150 °C via a reaction between the magnetite and copper incorporated in the oxide/Si-rich melt. The confirmation of such a reaction is supported by the observed misfit orientation (~10°) between the rim delafossite and magnetite. HAADF STEM imaging represents a hitherto underutilized tool for understanding pyrometallurgical processes, and offers a direct visualization of phase relationships at the smallest scale that can complement both experimental approaches and theoretical studies based on thermodynamic modelling.

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Section: Phase Associations: Exsolutions Versus Solid Solution and Gr...contrasting

confidence: 99%

“…In contrast to their restricted occurrence in the natural environment, Cu-bearing magnetite and delafossite are common co-existing phases in slags produced during copper smelting in flash furnaces (e.g., [21,22]).…”

Section: Introductionmentioning

confidence: 99%

Copper-Bearing Magnetite and Delafossite in Copper Smelter Slags

Gezzaz,

Ciobanu,

Cook

et al. 2023

Minerals

View full text Add to dashboard Cite

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“…[8] Hence, gaining more insight into the formation of accretions can help optimize the process and increase the boiler availability. [9] The following operational goals can be derived regarding flue dust management in the WHB:…”

Section: Introductionmentioning

confidence: 99%

Transient CFD Calculation of Accretion Formation in a Copper Waste Heat Boiler

Schmidt

Montenegro

Reuter

et al. 2022

Metall Mater Trans B

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The operation of a copper Flash Smelting Furnace (FSF) is often limited by the availability of the downstream Waste Heat Boiler (WHB). Carry-over of concentrate into the boiler leads to accretion formation, which can cause boiler downtime. Hence, the minimization of flue dust and its accretions is an important operational goal. In this study, a Computational Fluid Dynamics (CFD) model is used to investigate how three different baffle plate designs influence accretion formation over a period of 24 hours. The predicted dust accretion patterns were compared for all baffle plate modifications, with differences found both in the resulting sedimentation and accretion of dust particles. While the dispersive design led to large, but evenly coated accretion risk zones, a streamlined design minimized their size but led to locally thick accretion layers. Based on these findings, design recommendations for the baffle plate were derived.

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“…Comparable studies exist for the accretions from the gas uptake and radiation section. [19,27] Not only industrial experience but also Computational Fluid Dynamics (CFD) simulations can provide new insights into the complex flow behavior in the WHB. [4,7] Previous CFD studies focused on dust flow and settling in the radiation section.…”

Section: Introductionmentioning

confidence: 99%

CFD Study on the Physical Behavior of Flue Dust in an Industrial-Scale Copper Waste Heat Boiler

Schmidt

Montenegro

Reuter

et al. 2021

Metall Mater Trans B

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The Flash Smelting Furnace (FSF) is one of the most common reactors for the primary smelting of copper concentrates. Its smooth operation depends on the availability and performance of the downstream Waste Heat Boiler (WHB). The WHB is especially sensitive to problems with its flue dust handling, such as the formation of accretions, which can lead to downtime and equipment failures. Due to the limited accessibility and the harsh conditions of the WHB, experimental studies are challenging. Therefore, CFD simulations can be a promising option to increase knowledge and evaluate a range of options. The present study investigates the physical behavior of flue dust in an industrial-scale WHB via a three-dimensional CFD model. Size-dependent particle sedimentation and the risk areas for flue dust accretions are predicted, finding good agreement with industrial experience and data from the literature. To make the evaluation of accretion risk zones possible, a new sticking function for flue dust is developed. The results are validated against dust samples. Finally, operational recommendations for minimizing flue dust accretions are derived.

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Mineral chemistry and phase equilibrium constraints on the origin of accretions formed during copper flash smelting

Cited by 5 publications

References 7 publications

Copper-Bearing Magnetite and Delafossite in Copper Smelter Slags

Copper-Bearing Magnetite and Delafossite in Copper Smelter Slags

Transient CFD Calculation of Accretion Formation in a Copper Waste Heat Boiler

CFD Study on the Physical Behavior of Flue Dust in an Industrial-Scale Copper Waste Heat Boiler

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