Comparative Study of Spent Sand Reclamation from Binder Jetting and Conventional Foundry Technologies

The growing use of binder jetting in foundry practice has increased the need for effective recovery of the fine silica sand used in additively manufactured molds. This study examines mechanical and thermal reclamation of spent furfuryl-resin sands obtained from binder-jetted molds (US-1) and conventionally manufactured molds (US-2) after ductile iron casting. Mechanical reclamation was conducted at rotor speeds of 280-560 rpm for 10-30 min, whereas thermal reclamation was performed at nominal temperatures of 600-1000 °C. Reclaim quality was assessed using loss on ignition (LOI), pH, collected dust content, and bending strength, with grain morphology used to support the interpretation of the results. At 560 rpm for 30 min, the mechanical-reclamation efficiency index (W_RK) reached 31.5% for US-1 and 41.1% for US-2. At the highest nominal thermal-reclamation temperature after 30 min, LOI reached 0.14% and 0.29%, respectively. These results characterize each sand under the treatment and separation conditions applied to it. Different air-classification velocities-0.75 m/s for US-1 and 1.0 m/s for US-2-limit direct comparisons of collected dust, retained-matrix LOI, and the derived W_RK values. Together with differences in the initial sand characteristics, these classification conditions prevent differences between the systems from being attributed solely to the mold-manufacturing technology. Within each tested system, thermal reclamation achieved lower residual LOI, although selecting a process for practical use also requires an assessment of grain integrity and reuse performance.