废弃SCR催化剂中砷的二次释放行为研究

Study on Behavior of Arsenic Secondary Release from Waste SCR Catalyst

为了降低废弃SCR催化剂中砷的二次释放对环境的危害,文章应用XRD、XRF、SEM-EDS、ICP-OES等分析手段,采取柱浸出实验方法模拟自然降雨或水蚀条件下废弃SCR催化剂中砷的释放行为及特性,设计了砷的热释放在线监测系统,探索废弃SCR催化剂中砷在受热条件下的二次释放行为。结果表明:(1)废弃SCR催化剂中砷含量高达1.477%;(2)废弃SCR催化剂中砷在酸性水浴条件下(pH=5)析出率可达39.71%,析出率与水浴pH值呈负相关;(3)在受热条件下,废弃SCR催化剂中砷在800~1 000℃温度段可100%释放。因此,废弃SCR催化剂在储存及运输过程中应避免雨水冲刷,采用低温回收方法,可降低废弃或中毒SCR催化剂中砷的二次危害。

To reduce the hazard caused by the secondary release of arsenic(As)in waste SCR catalysts,a bench-scale experi-ment was conducted with analytic instruments including XRD,XRF,SEM-EDS and ICP-OES,and for observing As second-ary release behavior a leaching device was designed and set up to simulate the As secondary release of waste SCR catalysts in the condition of natural precipitation and water erosion.In addition,an online system was developed for monitoring As being released out of waste SCR catalysts under heated condition.Consequently,the experiment indicated as contained in waste SCR catalysts was as high as up to 1.477%.The rate of As separated out from the waste SCR catalyst was 39.71%under the condition of acid condition(pH of 5),the rate of As separation being negatively correlated to the pH value of the leaching water;and at the temperature 800~1000℃the releasing ratio of As could be up to 100%.Therefore,the discarded waste SCR catalysts during the period of storage and transportation should avoid rainwater flushing,and when recycling waste SCR cata-lysts it is necessary to adopt low-temperature recycling approaches to lower the secondary pollution of arsenic.