The Separation of Aluminum and Stainless-Steel Scraps Using Vibrating Mixed-Size Ball Bed

Hyunjin Na,Manis Kumar Jha,Kyoungkeun Yoo,Carlito Baltazar Tabelin

doi:10.3390/met10070868

Hyunjin Na, Manis Kumar Jha + Show 2 more

Open Access

https://doi.org/10.3390/met10070868

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Abstract

Dry gravity separation using a vibrating zirconia ball bed is proposed in this study to separate aluminum (Al) and stainless steel (STS) scraps obtained from spent hard disk drive recycling. The effects of zirconia ball sizes and vibrating power (vibration amplitude) on the separation efficiency of Al and STS scraps were investigated. The zirconia balls moved down at the center of the vessel and rose with the wall during the vibration test. Although more STS scraps sunk than Al scraps did, the separation efficiency was not maintained because Al scraps also sunk along with balls’ movement. The separation efficiency increased to 86.6% using 1-mm zirconia balls with a 2.5-mm vibration amplitude at 4 min, but it decreased rapidly by ball moving. Therefore, when a ball bed of mixed sizes (2:1 ratio of 1 and 3 mm) was used and arranged, whereby the 3-mm zirconia balls were above the 1-mm ball bed, the separation efficiency increased to 100% for more than 2 min. This dramatic improvement was because the 3-mm ball bed acted as a barrier to prevent sunken STS scraps from rising, and Al scrap cannot sink through the 3-mm ball bed. These results indicate that the separation of Al and STS scraps could be achieved successfully using the dry gravity separation method.

Highlights

Hard disk drives (HDDs), the most recognizable electronic storage device [1], have recently been replaced by solid state drives in personal computers [2]
The printed circuit boards (PCBs) accounts for 82.5% of the economic values of HDD, and rare earth elements (REE) such as Nd have been recognized as a strategic resource [11]
Each of the four Al and stainless steel (STS) scraps were placed on the ball bed, the vessel was vibrated for 10 min with predetermined vibration amplitudes

Summary

Introduction

Hard disk drives (HDDs), the most recognizable electronic storage device [1], have recently been replaced by solid state drives in personal computers [2]. Recycling has been suggested to recover valuable metals from HDD PCBs and NdFeB magnets. A new process for recycling and destroying data in spent HDD was proposed as follows. Gravity separation techniques such as jigging use water as a medium [12], which requires the drying of products after separation. The vibrating particulate bed method was applied recently to recycling processes as follows [17,18,19]. For spent HDD recycling, the present study is aimed at developing the dry-gravity separation of. Al and STS scraps using vibrating ball beds, which has not been studied before. The behavior of Al and STS scraps was examined by using a ball bed medium of mixed sizes to maintain high separation efficiency

Materials and Methods

Results and Discussion

Thebut separation efficiency with shown

10. Separation efficiencies of Al