Evaluation Method of Metal Resource Recyclability Based on Thermodynamic Analysis

Abstract

Currently, several metals are commercially recycled from by-products and wastes by metallurgical processing. However, the metallurgical process has each characteristic, which causes limitation for resource recovery. The combinations of elements in secondary resources, such as byproducts and wastes, are often different from those in natural resources. There are even combinations that are not present in natural resources. Conventional metallurgical processes have been optimized for economical and efficient extraction of desired elements only from large amount of ores under constant grade. Therefore, in order to extract metals from secondary resources by the conventional metallurgical process, it is necessary to estimate the recoverability of the constituent elements by taking into account their chemical properties well in advance. In particular, analysis for combination of elements is significantly important.In this study, we developed the evaluation method of metal resources recyclability based on thermodynamic analysis, and made clear the element distribution among gas, slag and metal phases during metal recovery based on thermodynamic analysis. In an application of the method shows that Cu, and precious metals (Ag, Au, Pt, Pd) present in mobile phones can be recovered as metals in the pyrometallurgy process of Cu in a converter, while Pb and Zn can be recovered as vapor. Other elements distributed in the slag phase are difficult to recover. The result of our analysis reflects the trends observed in the distribution of metals in copper metallurgy, thereby indicating the validity of our proposed evaluation method.

Material efficiency: rare and critical metals

“…Putting it another way, to close the material life cycle more effectively, the composition of the scrap must be very precisely known so as to optimize the recovery process [73]. For instance, it is impossible, at present, to separate copper or aluminium contaminants from remelted scrap iron or steel.…”

Thermodynamic criteria for the removal of impurities from end-of-life magnesium alloys by evaporation and flux treatment

“…Nakajima et al [9][10][11] have discussed the recyclability of steel, copper, lead, zinc and aluminum products from secondary resources and the limitations on impurity removal in the pyrometallurgical process on the basis of chemical thermodynamics. The element radar charts shown in these studies provide useful information for understanding which minor elements are connected to which commodity metals and which metals can be economically recovered with present-day facilities.…”

“…The distribution tendencies of elements in the remelting processes of steel, copper, lead, zinc and aluminum have been examined in previous studies [9,10]. Since the thermodynamic criteria on impurity removal from EoL magnesium alloys by oxidation and evaporation have also been developed in this work, the removability of impurity elements for these metals and magnesium can be compared.…”

“…In our previous papers, the thermodynamic criteria for impurity removal from remelted base metals such as steel, copper, lead, zinc and aluminum have been extensively discussed [9][10][11]. The objective of the present paper is to identify quantitative criteria for evaluating the possibility of removing impurities during the magnesium remelting process by considering all the relevant thermodynamic parameters.…”

Evaluation of Total Materials Requirement for the Recycling of Elements and Materials (Urban Ore TMR) from End-of-Life Electric Home Appliances

“…Nakajima et al developed the evaluation method of metal resources recyclability based on thermodynamic analysis, and made clear the element distribution among gas, slag and metal phases during metal recovery. 34) In near future, UO-TMR considering the yield rate will be estimated by applying their method, resulting in the reflection of the actual condition.…”