conventional starches are chemically crosslinked for use as selective depressants in the flotation of non - sulfide mineral ores . the process employing these crosslinked starches requires lower reagent dosages , exhibits improved selectivity and recovery and exerts a lower load on existing waste treatment facilities . the crosslinking agents employed are bifunctional and are used in sufficient quantities to result in 500 to 10 , 000 anhydroglucose units per crosslink .