焚烧飞灰由于含有大量氯化物等可溶性有毒物质限制了其应用范围.水洗作为最有效的预处理方式之一,可有效降低飞灰中氯、钠、钾等成分含量,提高水泥原料中飞灰投加量.本文从水洗生产线上收集三种等级的水洗飞灰,从多个方面分析其作为混合材的可行性.研究结果表明:三级水洗更能有效去除氯离子.三种水洗飞灰作为混合材后在掺量较低时能够促进水泥粉磨,在相同水洗细度下可节省粉磨时间,降低能耗.在掺量小于10%时不会缩短水泥凝结时间,同时能够提升水泥在不同龄期下的抗压强度.20%掺量下重金属的浸出满足《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3-2007)的要求.焚烧飞灰作为混合材后会降低水泥水化放热与Friedel盐生成量.考虑水洗后焚烧飞灰中各离子的限制,其最大掺量不应超过1.58%.综上,水洗焚烧飞灰有作为水泥混合材的潜力,去除有害离子后能够增大其在水泥工业中的应用范围.
Incineration fly ash is a kind of hazardous solid waste containing many soluble substances such as chlorides,it limits its application.As one of the most effective pre-treatment methods,water washing can effectively reduce the content of chlorine,sodium,potassium and other components in fly ash,and increase the amount of fly ash added in cement raw materials.This paper collected three grades of washed fly ash from the washing line to study its feasibility.The results showed that multiple washing can effectively remove chloride ions.The three types of washed fly ash could promote cement grinding at low dosing,shorten setting time,and reduce energy consumption with the same washing fineness.At a dosing rate of lower than 10%,it did not shorten the setting time of cement and could improve the compressive strength of cement at different ages.The heavy metal leaching at a 20%dosing rate satisfied the GB 5085.3-2007.Incineration of fly ash as blending material reduced the exothermic heat of hydration of the cement and generated new mineral-Friedel salts.If the limitation of each ion in the incineration fly ash after water washing is considered,the maximum admixture was lower than 1.58%.Therefore,washed incineration fly ash has the potential to be used as cement blending material.And its resource recovery capacity can be increased by removing the chloride ions and other factors.