水泥工业利废进展及前景

Progress of wastes reusing for cement industry and its prospect

水泥工业消纳利废的途径是将各种合适的废弃物或经适当加工预处理后的废弃物分别用作水泥的替代原料,或用作水泥窑的替代燃料,或用作混合材。相对而言,这三种利废方式中用作混合材是最简便易行的,来源也多;用作替代原料的往往具有一定的技术难度,来源较有限;用作替代燃料的难度最大,但各种可燃废弃物的来源却在日益扩大之中,数量也呈上升之势。然而,在中国水泥中混合材掺入量超标太多,而且大都作为填充料机械地掺入。今后必须严格监督执行国家标准(GB175-2007),坚决制裁超标或滥掺混合材的行径,加强发掘混合材活性的研发工作,从单纯追求数量转向提升质量的轨道上来。我国利用工业废渣作为替代水泥天然原料资源已取得一定成绩,但我国水泥工业始终对替代燃料不感兴趣,缺乏市场利益驱动,更谈不上什么协同全社会的环保利废责任感。笔者分析认为,在我国当前的具体情况下,一条5 000 t/d新型干法水泥生产线,采用可燃废料替代25%的煤耗时,其经济效益可与其增设纯低温余热发电的相媲美(包括CO_2减排CDM的收益在内)。

Ways for wastes reusing in cement industry consist in taking various proper wastes or properly pre-processed wastes separately as alternative raw materials,alternative fuels or additives in cement production.Within the three ways for wastes reusing,used as additives is the easiest way with vast sources,used as alternative raw materials is relatively difficult technically with limited sources,and used as alternative fuels is the most difficult way in practice,although sources for various combustible wastes are increasingly extended and their quantity are steadily increased. Nevertheless,mingled additives in cement are always far overdosed than the stipulations in Chinese standards,and most of them are simply mingled in as filling materials.From now on,state standard GB 175-2007 must be strictly executed and supervised to mete out severe punishment to someone who over-mingle or indiscriminately mingle additives in cement products.At the same time,R&D works for developing activeness of additives should be strengthened in order to turn the trends from seeking simply for quantity to raising the qualities.In China,using industrial wastes as alternative natural raw materials in cement production has got certain progress,but domestic cement enterprises are always not interested in alternative fuels because of a certain lack of market profit driving,still less dealing with the social responsibility for environmental protection and waste diminution.The author believe after analyzing that under the actual domestic conditions now,if adopting alternative fuels to substitute 25%of coal consumption for a 5,000 t/d PC cement production line,its economical profit can compare favorably with adding an additional power generation system using remnant heat from the production line(including CDM benefits from CO_2 emission reduction).