A new facile solvometallurgical leaching method for the selective Co dissolution &amp; recovery from hard metals waste

Amadou, Amadou Oumarou; Gaudenzi, Gian Pietro De; Marcheselli, Giancarlo; Cara, Stefano; Piredda, Martina; Spiga, Daniela; Matharu, Avtar S.; Gioannis, Giorgia De; Serpe, Angela

doi:10.1016/j.ijrmhm.2021.105534

“…This difference can be reasonably attributed to the lower values of the WC particles mean grain size and of the metallic binder mean free-path of the RC-631L test specimen, as found in previous studies on solvometallurgical processes on the same samples. 18 Additional characterization was performed on the solid residues after leaching to point out the stage of Co-dissolution and the state of the remaining W-based phases. In particular, powder Xray diffraction (p-XRD) and SEM/EDS analysis were made on the RC-631L sample before and after leaching with several of the systems under study.…”

Section: Leaching Experiments On Test Specimen Of Hm Powdersmentioning

confidence: 99%

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard metals waste enhancement

Amadou

¹

,

Cera

²

,

Piredda

³

et al. 2023

Preprint

0

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Peculiar chemical, mechanical and magnetic properties make cobalt a key metal for a variety of “hot” applications like cathode production of Li-ion batteries. Cobalt is also the preferred metallic binder for tungsten carbide tools manufacturing. The recent increasing criticality of cobalt and tungsten is driving the interest of manufacturers and researchers towards high-rate recycling of Hard Metals (HMs) waste for limiting the demand of raw materials. A simple and environmentally friendly hydrometallurgical route for Co selective dissolution from HM wastes was developed by using weak, bio-derived and biodegradable organic acids (OAs). In this study OAs, namely acetic (HAc), citric (H3Cit), maleic (H2Mal), lactic (HLac), succinic (H2Suc), lactobionic (HLB), and itaconic (H2It) acids, were selected for their pKa1 values spanning from 1.8 to 4.7 and systematically tested as selective cobalt leaching agents from WC-Co-based wastes in water, isolating the formed complexes at the solid state. Thereby, all of them seemed to be efficient in selective Co-leaching, achieving almost quantitative Co dissolution from HM by-products still at low concentration level and room conditions in a short time, leaving the residual WC unreacted and ready to be re-employed for industrial purposes. Nevertheless, two main categories of organic acids were distinguished depending on their oxidizing/complexing behavior: Class 1 OAs, where the metal oxidation is carried out by H+; Class 2 OAs where oxidation is played by an external oxidant like O2. A combined experimental/theoretical investigation is here described to show the reasons behind this peculiar behavior and laid the foundation for a wider discussion on the leaching capabilities of OAs towards elemental metals. Due to the demonstrated effectiveness, low cost, eco-friendliness and large availability through biotechnological fermentative processes, particular attention is here devoted to the use of HLac in hydrometallurgy as an example of Class 2 OA. WC-Co materials recovered by HLac mild hydrometallurgy demonstrated a metallurgical quality suitable for re-employment in the HM manufacturing process.

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“…Similarly, citric and acetic acids were satisfactorily employed as effective leaching agents for NbFeB magnets-where also Co, Ni, and several other REEs in low amounts are present in mild conditions, achieving material dissolution in a short time (Gergoric et al, 2018). Recently, we demonstrated the selectivity and efficacy of a new solvometallurgical Co-leaching method from HM powders based on the use of diluted maleic acid (H 2 Mal) ethanolic solutions working under gentle operative conditions (Oumarou Amadou et al, 2021). Specifically, H 2 Mal (0.5 M, EtOH) selectively and quantitatively leached Co trapped within WC-Co powders within 4 h at room temperature, leaving WC unreacted and ready for reemployment in HM manufacturing.…”

Section: Introductionmentioning

confidence: 99%

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard-metal waste enhancement

Amadou

¹

,

Cera

²

,

Trudu

³

et al. 2023

Front. Environ. Chem.

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Peculiar chemical, mechanical, and magnetic properties make cobalt a key metal for a variety of “hot” applications like the cathode production of Li-ion batteries. Cobalt is also the preferred metallic binder for tungsten carbide tool manufacturing. The recent increasing criticality of cobalt and tungsten is driving the interest of manufacturers and researchers toward high-rate recycling of hard-metal (HM) waste for limiting the demand for raw materials. A simple and environmentally friendly hydrometallurgical route for Co-selective dissolution from HM wastes was developed by using weak, bio-derived, and biodegradable organic acids (OAs). In this study, OAs, namely, acetic (HAc), citric (H3Cit), maleic (H2Mal), lactic (HLac), succinic (H2Suc), lactobionic (HLB), and itaconic (H2It) acids, were selected for their pKa1 values spanning from 1.8 to 4.7 and systematically tested as selective cobalt leaching agents from WC-Co-based wastes in water, isolating the formed complexes in the solid state. Thereby, all of them seemed to be efficient in selective Co leaching, achieving almost quantitative Co dissolution from HM by-products still at low concentration levels and room conditions in a short time, leaving the residual WC unreacted and ready to be re-employed for industrial purposes. Nevertheless, two main categories of organic acids were distinguished depending on their oxidizing/complexing behavior: class 1 OAs, where the metal oxidation is carried out by H+, and class 2 OAs, where oxidation is carried out by an external oxidant like O2. A combined experimental/theoretical investigation is described here to show the reasons behind this peculiar behavior and lay the foundation for a wider discussion on the leaching capabilities of OAs toward elemental metals. Due to the demonstrated effectiveness, low cost, eco-friendliness, and large availability through biotechnological fermentative processes, particular attention is devoted here to the use of HLac in hydrometallurgy as an example of class 2 OA. WC-Co materials recovered by HLac mild hydrometallurgy demonstrated a metallurgical quality suitable for re-employment in the HM manufacturing process.

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“…17 Recently, we demonstrated the selectivity and efficacy of a new solvometallurgical Co-leaching method from HM powders, based on the use of diluted maleic acid (H2Mal) ethanolic solutions working under gentle operative conditions. 18 Specifically, H2Mal (0.5 M, EtOH) selectively and quantitatively leached Co trapped within WC-Co powders, within 4 h at room temperature, leaving WC unreacted and ready for re-employment in HM manufacturing.…”

Section: Introductionmentioning

confidence: 99%

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard metals waste enhancement

Amadou

¹

,

Cera

²

,

Trudu

³

et al. 2023

Preprint

View full text Add to dashboard Cite

Peculiar chemical, mechanical and magnetic properties make cobalt a key metal for a variety of “hot” applications like cathode production of Li-ion batteries. Cobalt is also the preferred metallic binder for tungsten carbide tools manufacturing. The recent increasing criticality of cobalt and tungsten is driving the interest of manufacturers and researchers towards high-rate recycling of Hard Metals (HMs) waste for limiting the demand of raw materials. A simple and environmentally friendly hydrometallurgical route for Co selective dissolution from HM wastes was developed by using weak, bio-derived and biodegradable organic acids (OAs). In this study OAs, namely acetic (HAc), citric (H3Cit), maleic (H2Mal), lactic (HLac), succinic (H2Suc), lactobionic (HLB), and itaconic (H2It) acids, were selected for their pKa1 values spanning from 1.8 to 4.7 and systematically tested as selective cobalt leaching agents from WC-Co-based wastes in water, isolating the formed complexes at the solid state. Thereby, all of them seemed to be efficient in selective Co-leaching, achieving almost quantitative Co dissolution from HM by-products still at low concentration level and room conditions in a short time, leaving the residual WC unreacted and ready to be re-employed for industrial purposes. Nevertheless, two main categories of organic acids were distinguished depending on their oxidizing/complexing behavior: Class 1 OAs, where the metal oxidation is carried out by H+; Class 2 OAs where oxidation is played by an external oxidant like O2. A combined experimental/theoretical investigation is here described to show the reasons behind this peculiar behavior and laid the foundation for a wider discussion on the leaching capabilities of OAs towards elemental metals. Due to the demonstrated effectiveness, low cost, eco-friendliness and large availability through biotechnological fermentative processes, particular attention is here devoted to the use of HLac in hydrometallurgy as an example of Class 2 OA. WC-Co materials recovered by HLac mild hydrometallurgy demonstrated a metallurgical quality suitable for re-employment in the HM manufacturing process.

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A new facile solvometallurgical leaching method for the selective Co dissolution & recovery from hard metals waste

Cited by 7 publications

References 28 publications

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard metals waste enhancement

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard metals waste enhancement

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard-metal waste enhancement

A comparison among bio-derived acids as selective eco-friendly leaching agents for cobalt: the case study of hard metals waste enhancement

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