Resource recycling of superalloys and hydrometallurgical challenges

Selective anodic treatment of W(WC)-based superalloy scrap

“…Complete dissolution can be realized chemically, by treating with hot sulfuric acid [7], hydrochloric acid [7,11], hydrochloric acid with chlorine purging [7,12] or thermal reduction with carbon [7]. Pyrometallurgy methods are also used [7].…”

“…Pyrometallurgy methods are also used [7]. For complete dissolution, electrochemical methods are used, particularly anodic dissolution in sodium chloride solution, [4], acidic solution [7].…”

“…Pyrometallurgy methods are also used [7]. For complete dissolution, electrochemical methods are used, particularly anodic dissolution in sodium chloride solution, [4], acidic solution [7]. An electrochemical method has been employed in the work [11], but not for direct anodic dissolution of superalloy scrap, but for production of chlorine gas which oxidized superalloy surface that is prone to passivation.…”

“…However, the high corrosion resistance of superalloys complicates hydrometallurgical reprocessing [6]. It is proposed to employ other methods, which allows for not only reprocessing of materials into superalloys [7], but also for use of extracted components in other fields. For instance, recycling of Ni or Co binder is proposed [8].…”

Bio-Reclamation of Strategic and Energy Critical Metals from Secondary Resources

“…In that case, the criticality of metal can simply be presented as follows [4]: Criticality = Supply risk × Vulnerability = Likelihood of supply disruption × Economic Consequences (1) Notably, the availability of these metals largely influences the energy supply; country's economy, export business, job creation and geopolitical relation of two individual countries [5], hence can also be Notably, the availability of these metals largely influences the energy supply; country's economy, export business, job creation and geopolitical relation of two individual countries [5], hence can also be pronounced as 'strategic critical metals'. Figure 1 presents the list of such metals, including uranium (the major source of non-fossil, nuclear fuel) and gold (widely used for plating other conductor materials besides its economic importance in global trade) [2,3,6]. In the scenario of a mineral deficit country like Korea, all the metals shown in Figure 1 can be on the country's criticallist.…”