Recovery of Cerium from Glass Polishing Waste: A Critical Review

Abstract

Ceria is the main component in glass polishing powders due to its special physico-chemical properties. Glass polishing powder loses its polishing ability gradually during usage due to the accumulation of other compounds on the polishing powder or due to changes in the particle size distribution. The recovery of cerium from the glass polishing waste results in the efficient utilization of natural resources. This paper reviews processes for the recovery of rare earths from polishing waste. Glass polishing powder waste can be reused via physical, physico-chemical or chemical processes by removing silica and/or alumina. The removal of silica and/or alumina only improves the life span up to some extent. Therefore, removal of other elements by chemical processes is required to recover a cerium or cerium-rich product. However, cerium leaching from the polishing waste is challenging due to the difficulties associated with the dissolution of ceria. Therefore, high acid concentrations, high temperatures or costly reducing agents are required for cerium dissolution. After leaching, cerium can be extracted from the leach solution by solvent extraction or selective precipitation. The product can be used either in glass polishing again or other high value added applications.

Engineered nanomaterials in the context of global element cycles

“…70 However, larger volume applications (e.g., automobile catalysts, magnets, and polishing slurries) are potentially recyclable (e.g., Nd, Dy, and Ce). 70,136,137 Here, we note that REE recycling technology is an active area of research in private, government, 138,139 academic [140][141][142][143] and industry sectors, 144 and the US Department of Energy 145 is making substantial investments in recovery technologies, not only to overcome metal criticality, but also to improve national security as related to renewable energy and advanced electronic technologies.…”

Characterization and Feasibility Studies on Complete Recovery of Rare Earths from Glass Polishing Waste

“…REEs can be recovered from polishing waste by physical, physico-chemical and chemical methods [10]. However, it is difficult to remove all the impurities by physical separation due to their fine particle sizes.…”

“…The table shows that sample A (from plate glass polishing) contained a high amount of impurities like Ca, Si , Al, F and P. In sharp contrast, sample B (from mirror polishing) contained mainly F and P as the main impurities. Fluoride and phosphate are used for neutralizing the basic La oxide during polishing powder manufacturing [10]. Figure 1 shows the XRD patterns of two polishing waste samples.…”

“…Figure 5 shows the effect of acid concentration (2-5 M) on the recovery of REEs from two different waste samples by HCl acid leaching. The temperature (75 • C) and time (4 h) were chosen for the experiments based on literature data [10] and some preliminary experiments. The recovery of Ce and La increased with the increase in HCl concentration.…”

Sustainable Utilization of Metals-Processing, Recovery and Recycling

“…Recovery of these elements and thus securing of supply of raw materials independently of non-European market is still the focus of research today. Four papers deal with the recovery of REE [8][9][10][11].…”