| In this paper,the effect of water hardness on the flocculation behavior of fine-grained hematite under different conditions of deionized water,sodium oleate system and dodecylamine system was investigated by sedimentation test.In China,usually the water hardness refers to the total concentration of calcium and magnesium ions in water.In this paper,water hardness is characterized by the concentration of calcium and magnesium ions,and the effect on the flocculation behavior of hematite is studied.In order to investigate the mechanism of water hardness affecting the flocculation behavior of hematite,the surface tension of the solution after the addition of calcium and magnesium ions,the determination of the surface potential of hematite,and the analysis of the hydrolysis components of calcium and magnesium ions were performed.The settlement test showed that when the total concentration of calcium and magnesium ions in the ore slurry was in the range of 0 to 5.68 mmol/L,in the deionized water system,the flocculation behavior of hematite increased with the increase of water hardness;in sodium oleate systems,the hardness of pulp water increases,and the flocculation behavior of hematite increases first and then weakens,in the dodecylamine system,the flocculation behavior of hematite usually increases gradually with the increase of the hardness of pulp water;when the slurry p H value is in the range of 6 to12 internally,in the ore slurry containing the same concentration of calcium and magnesium ions,the flocculation behavior of hematite is generally enhanced as the p H value of the slurry increases.Under the selected experimental conditions,the effect of actual production water and laboratory-prepared water on the flocculation behavior of hematite is basically the same.The surface tension measurement results show that the addition of calcium and magnesium ions will increase the surface tension of the sodium oleate system solution,but have no significant effect on the deionized water and dodecylamine system.The Zeta potential test shows that the absolute value of the zeta potential on the hematite surface decreases with the increase of the hardness of the slurry water.The absolute value of the surface potential of hematite decreases,which reduces the repulsion of thedouble layer and contributes to the flocculation of hematite.The analysis of the hydrolysis components of calcium and magnesium ions showed that the main forms of calcium ions affecting the flocculation behavior of hematite include Ca2+,calcium hydroxide,Ca(OH)2,and the main forms of magnesium ions affecting the flocculation behavior of hematite include: Mg2+,magnesium hydroxy,Mg(OH)2.The settlement test and mechanism study results show that as the hardness of water increases,the absolute value of the zeta potential of hematite decreases,thereby reducing the repulsion of the double layer and contributing to hematite flocculation.When calcium and magnesium ions are present in the pulp in the form of metal ions,one monohydroxy compound,or a small amount of hydroxide,it is helpful for hematite to flocculation.When a large amount of calcium and magnesium ions exist in the pulp in the form of hydroxides,it is harmful for hematite to flocculation. |
