醋渣和糠醛渣对赤泥中金属稳定性的影响

Effects of Vinegar and Furfural Residue on Metal Stability in Bauxite Residue

赤泥中和是实现堆场植被复垦的必要途径,而醋渣和糠醛渣是赤泥降碱和改良效果较好的2种生物质材料.针对赤泥碱性降低过程中理化性质的改变,根据MEP(多级提取程序)毒性溶出以及BCR形态分级试验,对醋渣和糠醛渣对赤泥中金属行为的影响进行了研究.结果表明:添加20%的醋渣和糠醛渣后,赤泥pH从10.60分别降至9.61和8.96,w(TOC)从8.04 g/kg分别增至35.11和38.62 g/kg,赤泥比表面积从10.18 m2/g分别降至7.36和8.57 m2/g,CEC(阳离子交换量)从106.28 cmol/kg分别增至127.19和161.59 cmol/kg;赤泥中Mo的最低浸出浓度为0.37 mg/L,超过GB/T 14848—1993《地下水质量标准》中Mo的Ⅲ类标准限值(0.1 mg/L);醋渣和糠醛渣可有效抑制赤泥中Al、V、Pb的浸出,但却可促进Cu、Mn、Ni和Mo的浸出,四者的最高浸出浓度分别可达64.45、17.64、12.09μg/L和29.37 mg/L;醋渣和糠醛渣的添加可导致Al、V和Pb向稳定性较高的残渣态转化,Ni则向稳定性较低的酸可提取态转化.研究显示,糠醛渣比醋渣有更强的中和能力,对赤泥中金属稳定性影响较小.赤泥中金属元素具有潜在的长期浸出性且环境风险较高.

Bauxite residue neutralization is an essential way to achieve revegetation in bauxite residue storage areas,while vinegar residue and furfural residue are two kinds of biological materials for bauxite residue neutralization and amelioration. With consideration of the physicochemical property changes during alkalinity reduction,the effectiveness of two amendments on the metals behavior was investigated based on the experiments of MEP and BCR. The results indicated that the pH of bauxite residue after adding 20% of vinegar residue and furfural residue decreased from 10. 60 to 9. 61 and 8. 96,respectively,while TOC increased from 8. 04 g/kg to 35. 11 and 38. 62 g/kg,respectively. The specific surface area decreased from 10. 18 m2/g to 7. 36 and 8. 57 m2/g,respectively,and CEC increased from 106. 28cmol/kg to 127. 19 and 161. 59 cmol/kg,respectively. The minimum concentration of Mo was 0. 37 mg/L,which exceeded the Class Ⅲstandard limitation of 0. 1 mg/L according to the Quality Standard for Groundwater（ GB/T 14848-1993）. The vinegar residue and furfural residue could effectively restrain the leaching of Al,V and Pb,but promote the leaching of Cu,Mn,Ni and Mo. The highest leaching concentrations of Cu,Mn,Ni and Mo in the leachate were 64. 45,17. 64,12. 09 μg/L and 29. 37 mg/L,respectively. In addition,vinegar residue and furfural residue resulted in the transformation of Al,V and Pb to the residue fraction and Ni to the acid soluble fraction. The study showed that the furfural residue was more effective than vinegar residue to neutralize the bauxite residue,and it had less influence on the metals in bauxite residue. Metals in bauxite residue have a potential leaching property over the long term and have a high environmental risk.