淋溶气氛对AOD不锈钢渣中铬动态淋溶的影响

 AOD不锈钢渣(AOD渣)中的铬主要以三价态存在,但是在一定的条件下会被氧化从而以六价态释放至环境中造成生态破坏。以AOD渣为研究对象,采用长期动态淋溶的试验方法,研究了淋溶气氛对AOD渣中铬动态淋溶特性的影响。结果表明,淋溶气氛对浸出液氧化还原电位影响较为显著,空气气氛下氧化还原电位值在淋溶20 d之后明显高于氮气气氛;淋溶气氛对铬的淋溶能力有一定影响,空气气氛下初始淋溶液中的溶解氧会促进铬的浸出;在淋溶的前期,浸出液中的铬主要为Cr3+,而在淋溶后期,空气气氛下溶解氧的氧化作用开始显现,浸出液中出现较多的Cr6+;在空气气氛下,AOD渣中的铬会以比氮气气氛下更快的速率溶出,当淋溶进行到第44.6 d时,Cr3+的累积溶出率达到5.71%,Cr6+达到3.70%,总铬达到9.41%。AOD渣中的铬具有持续的溶出能力,淋溶毒性不容忽视。

Effect of leaching atmosphere on dynamic leaching characteristic of chromium in AOD stainless steel slag

The chromium in AOD stainless steel slag mainly exists in the trivalent state,but it will be oxidized and released into the environment in the hexavalent state under certain conditions,causing ecological damage. The AOD slag was the research object,and the long-term dynamic leaching experiment method was used to study the influence of leaching atmosphere on the dynamic leaching characteristics of Cr in AOD slag. The results showed that the leaching atmosphere had a significant effect on the redox potential (Eh) of the leachate,and the Eh value under the air atmosphere was significantly higher than the nitrogen atmosphere after 20 d of leaching; the leaching atmosphere had a certain influence on the leachability of Cr. The dissolved oxygen in the initial leaching solution in the air atmosphere could promote the leaching of chromium. In the early stage of leaching,the chromium in the leachate was mainly Cr3+,and in the late stage,the oxidation function of dissolved oxygen from the air atmosphere started to work, and more Cr6+appeared in the leachate. The air atmosphere promoted the dissolution of Cr at a faster rate than the nitrogen atmosphere. When the leaching progressed to the 44.6 d,the cumulative dissolution ratio of Cr3+ reached 5.71%,Cr6+ reached 3.70%,and the total Cr reached 9.41%. The chromium in the AOD slag had a continuous leaching ability,so its leaching toxicity cannot be ignored.