Garnet is one of the promising ceramic waste forms for immobilizing radioactive wastes. It has an A3 [VIII]B2 [VI]T3 [IV]O12 structure, so it can accommodate various cations of different sizes and coordination. Silicon usually occupies the centers of the tetrahedron structural site (T[IV]O4) in natural garnet. However, substitution of the T-site with iron, which has a relatively large ionic radius, causes the expansion of a unit cell volume of garnet and allows the incorporation of large cations such as actinides at other sites. Relatively few leaching data have been reported for ferrite garnet waste forms to date. In this study, we synthesized gadolinium-iron-garnet and evaluated the leaching property using cerium as a surrogate for actinide elements. The test specimens were made by cold pressing and sintering process. Three different standard leaching tests were performed as follows. The PCT-A (ASTM C1285) was performed for 7 days at 90°C to the crushed sample (0.149 to 0.074 mm). The ANSI/ANS-16.1 standard leach test was performed at ambient conditions for 5 days with constant replacement of leachate. Finally, the MCC-1 (ASTM C1220) test was performed for 28 days at 90°C with different types of leachants such as ultrapure water, brine, and silicate water. The last two leaching tests were conducted on monolithic specimens. After the end of the test, leachate was analyzed by inductively coupled plasma mass spectroscopy (Agilent, ICP-MS 7700S).

The waste casting sands generated from foundry is about 4,000 tons/day and the great part of them is handled by the method of reclamation and just 10% of them is recycled as a sand. This study is to produce the iron lump of high quality material through melting iron particle which is obtained from the waste casting sands. By using the high frequency inductive melting furnace after separating iron particle from casting sand by collision and vibrating classifier, iron lump is produced from melting iron particles. The iron lump of iron content of 96.95% is produced from iron particle of 68.05% through this process. It was investigated that the cost of iron lump is four times higher than the one of iron particle and to produce iron lump is worth to 325 won per kg against iron particle with considering the consumed power(electric energy). Therefore, to produce iron lump from waste casting sands is not only to be economical worth but also to strengthen the ground resources system.