Pollution prevention via recovery of cerium (IV) oxide in optics company

Zachary Hobbs,Eugene Park,William Gallagher,Mark Mayton

doi:10.1016/j.cscee.2020.100003

Abstract

Pollution prevention methods were applied at an optics manufacturer in an effort to improve recovery of a valuable polishing component, cerium oxide (ceria), 77% of which was lost to dragout and sewer discharge. Centrifugation and microfiltratiion were evaluated to develop a process that would increase recovery of used ceria, which would then be sent back to the ceria supplier for reclamation and reuse. Full-scale implementation included a high-speed centrifuge that operates continuously with a microfiltration system through recirculation in a single process tank. Sydor Optics has improved ceria recovery from 23% to 48%, saving thousands of dollars annually.

Highlights

Founded in 1964, Stefan Sydor Optics (Sydor) is a flat optics manufacturer located in Rochester, NY
Cerium oxide powders are used to polish a variety of glass surfaces such as those found on lenses, laser optics, light filters, mirrors, hard disk drives, photomasks, cell phone displays, and semiconductors
Due to the high cost of ceria, spent slurry solution is sent to Flint Creek Resources, where ceria is recovered for reuse at a lower purchase cost for Sydor via a patented process [1]

Summary

Introduction

Founded in 1964, Stefan Sydor Optics (Sydor) is a flat optics manufacturer located in Rochester, NY. Per marketing studies conducted by a ceria reclamation facility, Flint Creek Resources, the annual worldwide consumption of cerium oxide powders in 2011 was estimated to be 9,440 metric tons. Due to the high cost of ceria, spent slurry solution is sent to Flint Creek Resources, where ceria is recovered for reuse at a lower purchase cost for Sydor via a patented process [1]. Until 2017, the wastewater containing spent slurry from the machine washdowns was collected and filtered to remove large contaminants, centrifuged in a small, single-pass, basket centrifuge operating at 750 G’s and 2.0 L/min, and the remaining liquid discharged to sewer (Fig. 2). In 2015, the New York State Pollution Prevention Institute (NYSP2I) began working with Sydor to focus on the recovery of the spent ceria material and reduction of solids loading into the sewer system. This paper describes the work performed to evaluate technologies, design, and implement a system to recover more ceria and reduce TSS discharge from the ceria washwater operation

Materials and methods

Baseline determination

Evaluation of improvement opportunities through pilot-testing

Production system design

Metrics

Conclusion