DEPRESSION OF IRON-OXIDES WITH CORN STARCHES

A review of the industrial utilisation of corn starches in flotation, in Brazil, is presented with emphasis an iron oxides depression in the reverse cationic flotation of itabiritic ores. The current overall co nsumption reaches 40,000 metric tons per year, iron ores concentration representing approximately 80% of the total amount. The industrial re placement of very pure conventional starch (assaying over 98 % amylose + amylopectin on a dry basis) by coarser non conventional starches (c ontaining around 7% proteins + between 1% and 3% oil, beyond amylose amylopectin) is discussed. Some relevant aspects of different starch types are reported, highlighting an analysis of the action of the majo r individual components. The experimental results from microflotation tests in a modified Hallimond tube showed that zein, the most abundant corn protein, is a hematite depressant as efficient as amylopectin an d conventional corn starch. The poorest depression performance came fr om a non conventional starch with a high oil content. Copyright (C) 19 96 Published by Elsevier Science Ltd