氯化纳溶液对铝土矿矿泥的沉降影响

Effect of Sodium Chloride Solution on Sedimentation of Bauxite Slime

铝土矿尾矿泥浆因含有大量细粒与黏土矿物,导致其难以脱水沉降。而盐溶液的存在会影响黏土矿物颗粒间的作用力,进而影响其物理化学特性。为此,以广西铝土矿矿泥为例,采用不同浓度NaCl溶液对矿泥进行自由沉降试验和Zeta电位试验,并对沉降稳定后的矿泥进行电镜扫描,分析其微观结构。结果表明:随着NaCl溶液浓度增加,矿泥絮凝速率减小,沉降稳定孔隙比减小;Zeta电位绝对值随着溶液浓度增加而减小,反映了矿泥中黏土矿物颗粒表面负电荷被Na+中和后,双电层厚度变薄,颗粒间静电斥力减弱的现象;颗粒间排列结构形式由边-边结构(EE)向面-面结构(FF)过渡,从而导致颗粒间形成的聚团直径减小,絮凝速率变慢。但因排列结构的变化,颗粒间形成更为密实的堆叠结构,该分析与SEM分析结果一致。

The bauxite tailings slurry is difficult to dehydrate and settle due to its large amount of fine particles and clay minerals. The existence of salt solution will affect the force among clay mineral particles, thereby affecting their physical and chemical properties.Therefore, taking the bauxite slime in Guangxi as an example, the free sedimentation tests and Zeta potential tests on the slime were carried out with different concentrations of NaCl solution, and the slime after stable sedimentation was scanned by electron microscope to analyze its microstructure. The results show that with the increase of NaCl solution concentration, the flocculation rate of slime decreases and the settling stable pore ratio decreases. The absolute value of Zeta potential decreases with the increase of solution concentration, which reflects that the thinning of the double layer thickness and the weakening of the electrostatic repulsion among particles after the negative charge on the surface of clay mineral particles in slime is neutralized by Na+. The arrangement structures among particles transit from edge-edge structure to face-face structure, leading to the decrease of the cluster diameter formed among particles and the slow of flocculation rate. However, due to the change of arrangement structure, more dense stacking structures are formed among particles, which is consistent with the results of SEM analysis.