EFFECT OF ACID TREATMENT FOR COAL FLY ASH ON REMOVING HEAVY METALS UTILIZE AS A GEO-MATERIAL

摘要

Coal fly ash discharged from thermal power plants and other industrial activities is necessary to accelerate to utilize for various fields. It is possible to be a high performance material for geotechnical engineering field because of the light weight and having self-hardening characteristic. But there is some possibility of damaging environment or human health when it is used as a geo-material, because some heavy metals and alkaline compounds are contained in coal fly ash, and may leach out in the around. It is necessary for using coal fly ash as a geo-material to investigate and evaluate not only mechanical properties, but also environmental safety from the chemical view point. In this study, in order to reduce leaching heavy metals contained coal fly ash and to prevent pH of pore water from alkalinizing, we considered removing cause materials for toxicity of human health before using as a geo-material. And we carried out some fundamental experiments to investigate effects of acid treatment which is a removal method of cause materials. Results of this paper are as follows; (1) Removal quantity of Cr is more with increasing adding acid into the suspension of coal fly ash. (2) Quantity of Gr leaching from treated coal fly ash can be reduced by acid treatment. (3) Acid treatment can be prevented pore water of coal fly ash from alkalinizing.