Substituted Starches In Amine Flotation Of Iron Ore

PEARL starch, a corn starch prepared with a minimum of alteration, is a good selective depressant for iron oxide minerals.1 From what is known of the complex chemistry of corn starch, there is evidence that it consists of a mixture of saturated giant polymeric molecules, both straight and branch- chained, the constituents consisting of glucose units with hydroxyl radicals as active or polar groups. To add to the existing knowledge of the chemistry of the flotation process, it is desirable to ascertain the effects on the corn starch as an iron oxide depressant when some of the hydroxyl radicals are replaced by other active groups that are common to flotation reagents. The ideal way to carry out this investigation would be to test reagents containing different active groups derived from corn starch. The preparation should be such that the reagents possess the same degree and location of substitution and are ac- companied by little or no degradation of the starch molecules. This, of course, is almost impossible to realize, as it is difficult to control the degree and location of substitution as well as to prevent degradation of the starch molecule during preparation.