AOD渣中铬的短期淋溶特性

Short-term Leaching Characteristics of Chromium in the AOD Slag

在固体废弃物淋溶毒性测试标准的基础上,采用静态实验方法研究淋溶时间、固液比、溶解氧和溶液初始pH值对AOD渣中Cr的短期淋溶的影响。实验结果表明,AOD渣使淋溶液pH快速升高、E和DO快速降低;Cr淋溶呈现快淋溶和慢淋溶2个阶段,24 h内Cr淋溶基本达到平衡;尽管固液比对AOD渣淋溶液中Cr3+浓度的影响较小,但考虑到Cr3+与OH-间的平衡反应,直接采用固体废弃物淋溶毒性测试标准会低估Cr的淋溶量,从而过低评价Cr的淋溶毒性;短期淋溶过程中,溶解氧对Cr淋溶的影响相对较小;与中性淋溶液相比,碱性淋溶液对AOD渣中Cr的淋溶影响较小。而在酸性条件下,延长淋溶时间、降低溶液初始pH值将显著增加淋溶液中Cr3+的浓度。因此,采用中性淋溶液评价AOD中Cr淋溶毒性将显著低估Cr的淋溶毒性。

Based on solid waste leaching toxicity testing standards,using static test method to research the influence of leaching time,solid-liquid ratio,dissolved oxygen and initial pH value of solution on the short-term Cr leaching in AOD slag.The results indicated that the pH value of the leaching solution is rapidly increased,but E and DO are rapidly decreased by AOD slag;there are two phases of the leaching of Cr,namely fast leaching and slow leaching,the leaching of Cr reaches basic equilibrium within 24 h.Although the effect of solid-liquid ratio on the Cr3+ concentration in AOD slag leaching solution was less,solid waste leaching toxicity testing standards will underestimate the amount of leaching of Cr and its toxic due to the balance between the Cr3+ and OH-reaction;the influence of dissolved oxygen on the leaching Cr is relatively small in short-term leaching process;compared with neutral leaching solution,alkaline leaching solution has less effect on the leaching of Cr in AOD slag;under acid conditions,extending leaching time and reducing the initial pH value of the solution will significantly increase the concentration of the leaching solution of Cr3+.Therefore,the evaluation of neutral leaching solution for toxicity of Cr leaching in AOD slag will remarkably underestimate Cr leaching toxicity.