METHOD FOR TREATING FLYING ASH AND SOLIDIFIED MATERIAL CONTAINING NON-POLLUTED FLYING ASH

• Main Authors: UCHIDA MINORU, ONDA NOBUHIRO, ISHIKAWA AKIO, MOTOHASHI SATORU
• Format: Patent
• Language: English
• Published: 17.07.2001
• Edition: 7
• Subjects: CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS; CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING ORPROTECTING AGAINST HARMFUL CHEMICAL AGENTS; DISPOSAL OF SOLID WASTE; FIRE-FIGHTING; HUMAN NECESSITIES; LIFE-SAVING; PERFORMING OPERATIONS; RECLAMATION OF CONTAMINED SOIL SOIL; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a method advantageous for non-polluting hazardous flying ash and to obtain a solidified material which contains the non-polluted flying ash and has excellent handing quality. SOLUTION: This method for treating the flying ash containing dioxins and heavy metals consists of (i) a non-polluting treatment stage for bringing the flying ash into contact with an aqueous acidic solution held at a temperature lower than 100 deg.C and a pH in a range of 2 to 6 to extract heavy metal components in the flying ash into this aqueous solution and to crack the dioxins in the flying ash thereby making the dioxins non-polluting, (ii) a neutralizing treatment stage of adding an alkali to the non-polluting flying ash obtain by the non-polluting treatment stage and adjusting its pH to a range of 7.5 to 19 and (iii) a solidifying stage for adding a solidifying agent to the neutralized slurry liquid obtained in the neutralizing treatment stage to solidify the liquid. This solidified material has a structure to immobilize the non- polluting flying ash into the solidified material in the solidifying agent and the flying ash content in the solidified material is in a range of 7 to 40%, the metal-component content in the solidified material is in a range of 0.002 to 4% and the uniaxial compression strength of the solidified material is >=3 kgf/cm2.