电炉炼钢二噁英控制:活性炭吸附技术

CONTROL OF DIOXINS IN ELECTRIC STEELMAKING:ADSORPTION TECHNOLOGY BY ACTIVATED CARBON

随着电炉炼钢在我国钢铁生产领域的占比不断增大,炼钢过程所带来的二噁英污染问题也日益严峻。活性炭吸附技术是目前电炉炼钢企业脱除烟气中二噁英的主要手段。围绕适用于二噁英吸附的活性炭制备开展了一系列研究,结果表明:1)羟丙基甲基纤维素(HPMC)与低熔点玻璃粉(ST880)可作为新型绿色黏结剂用于活性炭成型,避免了煤焦油和沥青的使用,减少了活性炭生产过程中污染物的产生。HPMC为水溶性纤维素醚类衍生物,主要用来提高活性炭在高温活化前的耐磨强度;低熔点玻璃粉作为无机功能材料,具有优异的热稳定性和高温黏结性,保证了活性炭在高温活化过程不会破碎成粉、高温活化后仍具有较好的耐磨强度。2)根据二噁英吸附对活性炭孔结构参数的要求,采用简单的水蒸气活化法对成型活性炭进行了定向孔结构改造。适宜的液态水流量不仅关系到样品的产率,还会影响样品的孔隙性质。提高液态水流量,或在液态水总量一定时延长活化时间均有利于水蒸气在活性炭内部的扩散以及与碳原子的反应,容易得到中孔率较高的活性炭。在950℃下通入180 mL/h的液态水活化4 h,活性炭收率为50.1%,中孔体积为0.36 cm^(3)/g,所得样品对二噁英的脱除效率为90.9%。

With the increasing proportion of electric arc furnace(EAF)steelmaking in the field of steel production in China,the problem of dioxin pollution caused by the steelmaking process is getting worse.Activated carbon adsorption technology is considered to be the most promising strategy for removing dioxins from flue gas in the EAF steelmaking industry.In this paper,a systematic study was carried out on the preparation of activated carbon suitable for dioxin adsorption,and the main conclusion includes:1)hydroxypropyl methylcellulose(HPMC)and low-melting-point glass powder(ST880)can be used as a new type of green binder for activated carbon molding,avoiding the use of coal tar and asphalt,and reducing the production of pollutants in the process of activated carbon production.HPMC are water-soluble cellulose ether derivatives,which are mainly used to improve the abrasive resistance of activated carbon before high-temperature activation.As inorganic functional materials,low-melting-point glass powder has excellent thermal stability and high-temperature adhesion,ensuring that the formed activated carbon will not be broken into powder in the process of high-temperature activation,and still has a certain abrasive resistance after high-temperature activation.2)According to the requirements of dioxin adsorption on pore structure parameters of the activated carbon,the directional pore structure of formed activated carbon was modified by a simple water vapor activation strategy.The appropriate liquid water flow rate is not only related to the yield of the sample but also affects the pore properties.The improved liquid water flow and the improved activation time when the total amount of liquid water is constant are conducive to the diffusion of water vapor inside the activated carbon and the reaction with carbon atoms,and it is easy to obtain activated carbon with a high mesoporous ratio.The activated carbon was activated with 180 mL/h of water vapor at 950℃for 4 hours,the yield was 50.1%,and the mesopore volume was 0.36 cm^(3)/g.The removal efficiency of dioxin in activated carbon products was 90.9%.