Development of Technology for Raw Material of Ordinary Portland Cement and Practical Use of Sludge made from Steel Industry by Complex Treatment

Abstract

The purpose of this study is to use the waste sludges generated in steel making industries as a raw material of ordinary portland cement (OPC). In this study the characteristics of the sludges, suitable mix design of raw materials, the minerals synthesized, physical properties of clinker, effect of chlorine, and heavy metals for operations were investigated in a pilot kiln. As a result, it was found that the waste sludge mainly included CaO, SiO₂, Al₂O₃ and Fe₂O₃ which are the main components of OPC and components causing operation troubles in a kiln such as MgO, SO₃ and chlorine were also in the sludges. Most of the sludges were clogged in moisture content of 25∼30%. Coating in the kiln increased as the experiment was repeated. Main anions of the coated matter were SO₃^2- and Cl^-, and the content of SO₃^2- was 15.2%, Cl^-, 25, 414 ppm. Chlorine circulation behavior was simulated by the Weber model, and when the addition content of the sludge mixture was 3%, the suitable by-pass rate of chlorine was 2% in consideration of the chlorine limit value of 5, 000 ppm in a industrial cement plant. Main mineral phases, setting time and the compressive strength of cement produced were equal to those of OPC. About 50, 000 tons of clinkers were produced using the addition content of 1% and 2% in a cement plant. All the characteristics of the cement produced had no differences compared with OPC, and the circulation matter did not affect operations and cement quality.