Fundamental issues on the influence of starch in amine adsorption by quartz

Abstract Apart from being a resource for iron/steel production, the iron oxide mineral, hematite, is used in the paint, cosmetics, and other industries as a pigment. Reverse flotation of quartz from hematite is used extensively in the processing of iron ore containing quartz as the gangue mineral. It has been observed that depression of quartz takes place when excessive starch is used in the reverse flotation of iron ore, thus reducing the grade of the hematite concentrate. In the present work, the reason for the depression of quartz in the presence of excess starch has been investigated. Contact angle, bubble attachment time, quartz crystal micro balance with dissipation (QCM-D), and sum frequency vibrational spectroscopy (SFVS) measurements have been used to examine the interaction between mono ether amine and starch, and molecular dynamics simulation (MDS) was used to visualize the interaction between the amine and starch molecules. On the basis of these measurements it appears that a clathrate interaction takes place in such a way that the starch masks the hydrophobic tail of the mono ether amine, decreasing the contact angle at the quartz surface to 43° from 62° in the presence of excess starch.