Study On Physicochemical Modification Of Starch And Its Effect On Hematite Reverse Flotation

In our country,iron ore resources are abundant but not rich,difficult iron ore accounts for a large proportion,reverse flotation is one of the most widely used means for processing difficult iron ore at present,and inhibition ability of inhibitors plays an important role in reverse flotation index,development of iron ore reverse flotation inhibitors is of great significance for the development and utilization of difficult iron ore resources.In this study,under the cationic reverse flotation system of fine hematite,through flotation test,surface wettability test,selective flocculation test,solubility,Zeta potential,carboxyl/carbonyl group content,rheological test and XPS and AFM analysis,the effects of ultrasonic modification and ozone oxidation on the flotation inhibition of fine hematite by starch and its mechanism were studied from three aspects :the effect of modified starch on the flotation of fine hematite,the effect of modified treatment on the interaction between starch and minerals,and the effect on the physicochemical properties of starch.The main conclusions were as follows:The single mineral flotation test showed that ultrasonic treatment significantly improved the selective inhibition ability of starch to fine hematite.When ultrasonic modified starch was used instead of conventional caustic starch for mixed ore flotation,the iron concentrate grade and recovery of iron concentrate were increased by 1.99%～4.62% and 6.22%～6.31% respectively.Ultrasonic treatment can break the molecular chain of starch,and increase the solubility,acidity and amylose content of starch.These changes in physical and chemical properties improved the adsorption capacity of starch on the surface of hematite,made the surface of hematite more hydrophilic,and improved the inhibition ability of starch on the true flotation of fine hematite.At the same time,the selective flocculation ability of starch to fine hematite is improved and the entrainment of fine hematite in reverse flotation is reduced.The synergistic action of the above two points reduces the loss of micro-fine hematite in reverse flotation tailings and improves the inhibitory effect of starch on micro-fine hematite.Single mineral flotation tests show that ozonation can significantly improve the selective inhibition ability of starch to fine hematite in flotation.When ozoneoxidized starch was used to replace primary starch in mixed ore flotation,the iron concentrate grade and recovery rate of iron concentrate were increased by2.45%～3.44% and 6.6%～8.35%.Ozonization reduces starch chain length and oxidizes hydroxyl group to carboxyl group.It also increases the solubility of the starch.These changes in physical and chemical properties strengthen the adsorption of starch on the surface of fine-grained hematite,make the surface of hematite acted with starch more hydrophilic,improve the inhibition ability of starch on the true flotation of fine-grained hematite,and thus improve the inhibition effect of starch on fine-grained hematite.