ECOCEMENT Innovative Cement for Contributing to Sustainable Society

摘要

In Japan, a majority of urban waste is incinerated to reduce the volume and the residue (incineration ash) is land filled. Japanese municipalities, however, are confronted with serious shortages of waste landfill sites. To mitigate this situation, Taiheiyo Cement Corporation has developed two technologies, which are Ash Rinsing Process and Ecocement. Incineration ash is a suitable material for cement production because it primarily contains essential chemical components of cement clinker. The problem is that chlorine and heavy metals accompanying primary components cause operational trouble and deteriorate quality and material safety of cement. Ash rinsing technology will be effective to remove chlorine and heavy metals in the ash. Therefore, for municipalities closely located existing Ordinary Portland cement plants, it is the simplest way to use waste incineration ash as a raw material in those cement plants. Ecocemet, on the other hand, will be an attractive option for the municipalities distant from cement plants. Ecocement is defined as cement that is produced from over 500 kg (dry base) waste incineration ash supplemented with other wastes (sludge, etc) per ton of Ecocement. According to the discharged amount of ash, correspondingly scaled Ecocement plant is needed. In Ecocement production process, chlorine in the ash is combined with intentionally added alkalis or heavy metals and is extracted. Extracted metal chlorides are recycled as metal sources. Two types of Ecocement can be used in the fields of ready mixed concrete, concrete blocks or soil stabilizer. The first commercial plant of Ecocement constructed in Chiba prefecture started operation in April 2001. In July 2002, Japanese Industrial Standard of Ecocement was published. Consequently, Ecocement has become an authorized product In Japan. The second Ecocement plant is now under construction in Tokyo.