Trends and perspectives in the use of organic acids for critical metal recycling from hard-metal scraps

Cera, Martina; Trudu, Stefano; Amadou, Amadou Oumarou; Asunis, Fabiano; Farru, Gianluigi; Gaudenzi, Gian Pietro De; Gioannis, Giorgia De; Serpe, Angela

doi:10.1016/j.ijrmhm.2023.106249

Cited by 4 publications

(5 citation statements)

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“…Mishandling of inorganic acids may result in corrosion of equipment and infrastructure, harm to the environment and ecosystem through careless disposal, higher energy consumption through prolonged reaction times at elevated temperatures, etc. In this regard, the use of bio-derived organic acids is a solution [113]. Their easy availability, renewable nature, affordable cost, and safety features show promising results for metal leaching purposes.…”

Section: Progress In Bio-derived Sustainable Organic Acids For Leachi...mentioning

confidence: 99%

“…Additionally, their solubility in water (as well as in other green solvents, such as ethanol) is a bonus. The most widely reported organic acids used in leaching treatment of WC hard and soft scraps are acetic acid [57,95], succinic acid [114], lactic acid [114], itaconic acid [114], lactobionic and maltobionic acids, formic acid [113,114], malic acid [113,115], citric acid [104,112,114], tartaric acid [113], and maleic acid [114,116].…”

Section: Progress In Bio-derived Sustainable Organic Acids For Leachi...mentioning

confidence: 99%

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Progress in Sustainable Recycling and Circular Economy of Tungsten Carbide Hard Metal Scraps for Industry 5.0 and Onwards

et al. 2023

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In spite of the critical environmental impacts of mining and the associated geopolitical supply risk, the strategic importance of rare metal tungsten is escalated by rapid expansions in industrialization, particularly in the ongoing low-carbon/energy era, which requires technologies that allow an economic, social, and ecologically friendly tungsten recovery from primary and secondary resources. The current recycling practices of tungsten carbide (WC)-based scraps have been accepted as economically and partially environmentally beneficial and can promote tungsten closed-loop recycling; however, low functional recycling rates and significant metal losses at varied stages hinder the economic recovery of metals. The current review presents the global situation of tungsten and WC flow with a focus on various sustainable methods to recycle spent tungsten and related metals. A detailed discussion of establishing a highly resilient circular economy with sustainable development goals is highlighted by juxtaposing the philosophy of the circular economy, integrated sustainability, and the metal life cycle approach. The article also discusses Industry 5.0 trends, such as sustainable digitalization and twin transition, to overcome the barriers associated with achieving efficient circular recycling. It is shown that cross-disciplinary methodologies, the integration of diverse technologies (digital/green), and the incorporation of state-of-the-art recycling techniques open up the future potential in the recycling sector.

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Section: Progress In Bio-derived Sustainable Organic Acids For Leachi...mentioning

confidence: 99%

Section: Progress In Bio-derived Sustainable Organic Acids For Leachi...mentioning

confidence: 99%

Progress in Sustainable Recycling and Circular Economy of Tungsten Carbide Hard Metal Scraps for Industry 5.0 and Onwards

et al. 2023

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“…Currently, a variety of methods for the enhancement of cobaltcontaining waste generally exploit the use of dangerous reagents (primarily strong oxidizing acids) and/or aggressive operating conditions (high temperatures) (Zeiler et al, 2021;Konyashin et al, 2022b). In the last decade, the use of bio-derived organic acids (OAs) as leaching agents has gained increasing attention for being safe, renewable, and, in some cases, cheap substances (Burckhard et al, 1995;Musariri et al, 2019;Cera et al, 2023). Thanks to their capability to dissolve low-reduction potential metals, some of them have been recently proposed as suitable leaching agents for the transition and recovery of rare earth 1 elements from several kinds of waste.…”

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

Cera

Trudu

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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“…Circular use of these elements, as well as of additives, is thus mandatory and raw materials recovery in the HM field is common practice. HM recovery can be carried out in different ways [7] and gathered under direct recycling [8][9][10][11][12][13][14], indirect chemical recycling [15][16][17][18][19] and melting metallurgy [20]. All recovery routes included in these groups, attempted or implemented, exhibit different drawbacks.…”

Section: Introductionmentioning

confidence: 99%

“…Through the dissolution of the metal, the integrity of the carbide structure is lowered and easily disintegrated [7]. Moreover, environmentally benign leaching agents are being investigated [18,19].…”

Section: Introductionmentioning

confidence: 99%

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Bozzini,

Tavola,

Travella

et al. 2023

Metals

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Recycling of hardmetal scrap is strategic for critical raw materials recovery. Available recycling processes are polluting and have a large carbon footprint. Attempts to exploit controlled corrosion failed in industrial practice, owing to self-limiting processes. We revisit the corrosion route, in view of gaining the fundamental knowledge enabling high-throughput recovery. We selected the worst-case approach of highly corrosion-resistant CoNiWC-based hardmetal grades and neutral aqueous electrolyte at room temperature. Systematic electrochemical measurements, UV–Vis spectroscopy and SEM microscopy disclosed that, even though there is no hope to overcome the self-limiting corrosion rate, nevertheless, by exploiting the mechanical action of anodic O2 evolution acting precisely at the interface between the residual active material and the corrosion film, the latter can be efficiently removed, periodically reactivating the hardmetal corrosion in a way that results in an ultra-high scrap destruction rate, of interest for real-life industrial processes.

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Trends and perspectives in the use of organic acids for critical metal recycling from hard-metal scraps

Cited by 4 publications

References 66 publications

Progress in Sustainable Recycling and Circular Economy of Tungsten Carbide Hard Metal Scraps for Industry 5.0 and Onwards

Progress in Sustainable Recycling and Circular Economy of Tungsten Carbide Hard Metal Scraps for Industry 5.0 and Onwards

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

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

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