Papers by Author: Seung Whee Rhee

Abstract: Thermal stabilization is used to reduce the turbidity of spent foundry sands (SFSs). Effect of stabilized temperature and thermal stabilized time in thermal stabilization is estimated by turbidity of SFSs in thermal stabilization. The turbidity of furan sand is 984 FAU and almost 15 times as high as that of other sands such as CO2 sand and green sand. Furan sand contains furan resin, but CO2 sand and green sand do not use resin chemicals. The turbidity of furan sand can be reduced by stabilization of furan resin in thermal process. In the process of thermal stabilization, fixation of furan resin by heating occurs and resin can be in the state of insolubility. The turbidity of furan sand is sharply decreased within thermally stabilized time of 2 hrs and decreased with increasing stabilized temperature. Turbidity in thermal stabilized time of 2hrs and stabilized temperature of 600°C is almost 10 FAU. Hence, thermal stabilization can be applied to reduce the turbidity of SFSs generated from iron foundry industry.

Abstract: Spent foundry sand (SFS) from cast iron industry mixed with loess was characterized to recycle spent foundry sand as ceramic support materials. Since SFS mostly consists of sand including binding agents and residue [1], it was used as permeable media, and loess, which has highly adsorptive and reactive properties, was used as support materials Leaching tests such as Korean Leaching Test (KLT) and TCLP (Toxicity Characteristics Leaching Procedure) showed that spent foundry sands from cast iron industry were not hazardous. Turbidity in furan sand was much higher than that in other sands, and turbidity was almost not changed with increasing amount of loess. The order of ORP (oxidation-reduction potential) in spent foundry sands was green sand > furan sand > CO2 sand. ORP was decreased with the amount of sand in furan sand and CO2 sand but was increased with the amount of sand in green sand. Hence, mixture of SFS and loess can be used as ceramic support materials with reductive or oxidative capability.

Abstract: The objective of this study is to prepare a pelletized adsorbent to remove volatile organic compounds (VOC) from the municipal solid waste incinerator (MSWI) fly ash in Korea. The fly ash sample was sieved to particle size of 75-150㎛, and then a hydrothermal processing was carried out. The pelletized adsorbent was prepared from hydrothermal treated fly ash by mixing it with coal tar pitch and K2CO3 as a carbon source and activating agent, and activating them. The optimum condition to derive maximum iodine adsorptivity and BET surface area was the mixing ratio of hydrothermal treated fly ash, coal tar pitch and K2CO3 of 40/40/20 wt.% at the activation temperature of 800°C. Under this condition, the iodine adsorptivity and BET surface area for prepared adsorbent were 455 mg/g and 325 m2/g, respectively.