V-Ti磁铁矿尾矿(VTMT)含有各种重金属,比如Fe,Mn,V,Co,和Ni。尾矿金属释放造成的地下水污染已成为当地环境关注的问题。尽管研究已经证明了交替的驱油和干燥循环(FDC)对矿物中金属形态和流动性的影响,关于FDC是否影响VTMT的金属释放和释放金属的转化知之甚少。这项研究调查了在不存在和存在酸雨(硫酸和硝酸)和生物分泌的有机酸(乙酸,草酸,和柠檬酸)。结果表明,无论是否存在酸,FDC都会促进金属释放。V的最大释放浓度,Mn,Fe,Co,和Ni分别高达78.63mgL-1、1.47mgL-1、67.96μgL-1、1.34mgL-1和0.80mgL-1,在FDC和柠檬酸下。FDC通过增加金属不稳定部分的比例来增强尾矿金属的释放。然而,释放的铁的浓度,Mn,V,Co,Ni和Ni均由于其(共)沉淀而逐渐减少。相反,这些沉淀物通过覆盖尾矿表面来抑制随后的矿物溶解。FDC还将尾矿的孔隙率提高了2.94%至9.94%。矿物溶解,膨胀和收缩,张力的变化破坏了FDC过程中的尾矿微观结构。这项研究证明了VTMT在FDC下的低金属污染风险,无论是在酸雨或生物分泌的有机酸。然而,应认真考虑尾矿孔隙度的增加,因为它会影响尾矿库的安全。
V-Ti magnetite tailings (VTMTs) contain various heavy metals, such as Fe, Mn, V, Co, and Ni. The groundwater pollution caused by the tailing metal release has become a local environmental concern. Although studies have demonstrated the influence of alternate flooding and drying cycles (FDCs) on metal form and mobility in minerals, little was known about whether FDCs affect the metal release of VTMTs and the transformation of released metals. This study investigated the metal release kinetics of VTMTs and the metal transformation under FDCs in the absence and presence of acid rain (sulfuric and nitric acids) and bio-secreted organic acids (acetic, oxalic, and citric acids). The results showed that FDCs promoted metal release whether or not acids were present. The maximum released concentrations of V, Mn, Fe, Co, and Ni were as high as 78.63 mg L-1,1.47 mg L-1, 67.96 μg L-1, 1.34 mg L-1, and 0.80 mg L-1, respectively, under FDCs and citric acids. FDCs enhanced the tailing metal release by increasing the metal labile fraction proportion. However, the concentrations of released Fe, Mn, V, Co, and Ni all gradually decreased due to their (co-)precipitation. These precipitates conversely inhibited the subsequent mineral dissolution by covering the tailing surface. FDCs also enhanced the tailings\' porosities by 2.94%-9.94%. The mineral dissolution, expansion and shrinkage, and changes in tension destroyed the tailing microstructure during FDCs. This study demonstrated the low metal pollution risk of VTMTs under FDCs, either in acid rain or bio-secreted organic acids. However, the increase in tailing porosity should be seriously considered as it would affect the tailing pond safety.