Efficient Recycling Process of Waste Sand with Inorganic Binder via Ultrasonic Treatment

The conventional recycling processes for waste sand with inorganic binder (WSIB) in aluminum alloy casting involve washing, heat treatment, and mechanical grinding. However, this process is complex and inefficient for removing the residual binder on the surface of WSIB. This study proposes a simplified and effective recycling process using ultrasound treatment to more efficiently remove residual binder on the surface of WSIB. To evaluate its effectiveness, we characterized ultrasonically recycled sand (URS), conventionally recycled sand (CRS), and virgin sand (VS). The evaluation consisted of the following three steps: (1) characteristics of sand, such as residual binder content, particle size distribution, surface morphology, and specific surface area; (2) measuring the properties of sand cores, including bending strength and the volume of gas evolved during the pouring of A356 Al melts; and (3) measurement of porosity level at the interface between the sand core and A356 Al castings. These results indicate that the ultrasonic recycling process can achieve a technically efficient and simplified recycling process for WSIB.