The purpose of this study was to verify safe and environmentally-sound recycling of blast-furnace slag in the cement industry. This was accomplished by analyzing the heavy metal contents of three kinds of raw materials: blast-furnace slag, Portland cement, and the substitutes, which were mainly input into the manufacture of cement. The research revealed that, in the five samples tested, the heavy metal level in the blast-furnace slag cements (5.90 ~ 8.38 mg/kg for Cr6+) is lower than the ordinary Portland cement (11.04 ~ 14.92 mg/kg for Cr6+). This suggests that both raw materials have low heavy metal contents compared with the 20 mg/kg limit enforced by the autonomic convention in Korea. As for the substitutes, there was no decisive effect on the overall heavy metal content because of the low input ratio of 2.5%. Therefore, it is of high utility value to recycle the blast-furnace slag in the cement industry, considering slag can dilute the overall heavy metal contents in the cement products.

Abstract
 I. 서 론
 II. 연구내용 및 방법
  1. 시료채취현황
  2. 분석방법
 III. 결과 및 고찰
  1. 보통 포틀랜드 시멘트
  2. 고로슬래그
  3. 고로슬래그 시멘트의 대체원료
  4. 고로슬래그 시멘트
 IV. 결 론
 References

• 김용준(국립환경과학원 자원순환연구과)
• 엄남일(국립환경과학원 자원순환연구과)
• 강영렬(국립환경과학원 자원순환연구과)
• 오정근(국립환경과학원 자원순환연구과)
• 신선경(국립환경과학원 자원순환연구과)
• 이영기(국립환경과학원 자원순환연구과)
• 김기헌(국립환경과학원 자원순환연구과) Corresponding author