The utility of employing biogenerated ferric iron as an oxidant for the recycling of scrap metal has been demonstrated using continuously growing cells of the extremophilic organism Acidithiobacillus ferrooxidans. A ferric iron rich (70 mol%) lixiviant resulting from bioreactor based growth of A. ferrooxidans readily solubilized target scrap metal with the resultant generation of a leachate containing elevated ferrous iron levels and solubilized copper previously resident in the scrap metal. Recovery of the copper value was easily accomplished via a cementation reaction and the clarified leachate containing a replenished level of ferrous iron as growth substrate was shown to support the growth of A. ferrooxidans and be fully recyclable. The described process for scrap metal recycling and copper recovery was shown to be efficient and economically attractive. Additionally, the utility of employing the E(h) of the growth medium as a means for monitoring fluctuations in cell density in cultures of A. ferrooxidans is demonstrated.
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Spectrochim Acta A Mol Biomol Spectrosc
December 2024
TECNALIA, Basque Research and Technology Alliance (BRTA), Parque Tecnológico de Bizkaia, C/ Geldo. Edificio 700, E-48160, Derio - Bizkaia, Spain; University of the Basque Country, Plaza Torres Quevedo, 48013 Bilbao, Spain.
Materials (Basel)
November 2024
School of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China.
We conducted a mechanistic and experimental study on zinc fluoride roasting for the recovery of NdFeB waste to address the difficulties faced during this pyrometallurgical recovery process, such as the high dependence on the quality of raw materials, the high energy consumption involved in roasting transformations, and the low added value of mixed rare earth products. Thermodynamic calculations showed the feasibility of fluorinating rare earths in NdFeB waste, and one-factor experiments were performed. The results showed that at a roasting temperature of 850 °C, a reaction time of 90 min, and 100% ZnF addition, the fluorination rate of rare earths could reach 95.
View Article and Find Full Text PDFNat Commun
December 2024
Pacific Northwest National Laboratory, Richland, WA, USA.
Although recycling secondary aluminum can lead to energy consumption reduction compared to primary aluminum manufacturing, products produced by traditional melt-based recycling processes are inherently limited in terms of alloy composition and microstructure, and thus final properties. To overcome the constraints associated with melting, we have developed a solid-phase recycling and simultaneous alloying method. This innovative process enables the alloying of 6063 aluminum scrap with copper, zinc, and magnesium to form a nanocluster-strengthened high-performance aluminum alloy with a composition and properties akin to 7075 aluminum alloy.
View Article and Find Full Text PDFInt J Environ Health Res
November 2024
Environmental Engineering Research Laboratory, Obafemi Awolowo University, Ile-Ife, Nigeria.
The growing demand for ferrous metals and abundant scrap materials has fueled Nigeria's scrap-iron smelting industry, leading to hazardous pollutant emissions. This study investigated the concentrations, seasonal and indoor-outdoor variations, origins, and health impacts of polycyclic aromatic hydrocarbons (PAHs) in dust samples around a scrap-iron smelting facility. Analyses of dust samples revealed that high molecular weight PAHs (HMWPAHs) dominated during both seasons, with 5-ring PAHs (34%) contributing most during the rainy season and 3-ring PAHs (36%) during the dry season.
View Article and Find Full Text PDFChemosphere
November 2024
BOSK-Bioproducts, 100-399 rue jacquard, Quebec, QC, G1N4J6, Canada; Research Centre for Eco-Environmental Engineering, Dongguan University of Technology, China.
This research paper deals with a novel method utilizing packed bed electrocoagulation (PBEC) comprising of sacrificial iron electrodes and coupled with extracellular polymeric substances (EPS) used as flocculent agents for the treatment of commercial laundry wastewater (LWW). The study employs stainless steel cathodes, graphite anodes, and scrap iron pieces as sacrificial electrodes, ensuring efficient treatment in dynamic batch mode operation with enhanced contact time facilitated by serpentine flow. The initial characteristics of LWW were COD 579 ± 30 mg/L, TSS of 60 ± 10 mg/L, TS of 622 ± 20 mg/L, turbidity of 110 ± 5 NTU, pH of 9 ± 0.
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