Abstract: Comparative laboratory tests of reverse flotation were carried out on improving the 42.00% low grade mixed iron concentrate from magnetic separation of an iron concentrator by cyclonic static micro-bubble flotation column. The results showed that by one roughing, the concentrate grade of the flotation column was about 67%, three percentage points higher than that of flotation cell. However, the tailing had also a higher grade. For this, improvement was made on the flotation column by adding a pulsating magnetic system and flow-stabilizing pipe. The improved flotation column not only keeps the advantage of high concentrate grade but can greatly reduce the tailing grade. One roughing can obtain a concentrate grading 67.85% at a recovery of 79.22%. To achieve the similar indexes, the flotation cell needs one coughing, one cleaning and three scavengings.

Key words: Cyclonic static micro-bubble flotation column, iron concentrate from magnetic separation, reverse flotation