Studies on Recovery of Iron From the Tailings of Arcelormittal Concentrator Plant, Serra Azul, Brazil

The iron ore beneficiation plant at Serra-Azul Mines of ArcelorMittal, Brazil operates at a rated capacity of 3.2 million tons per year. The ore is concentrated using magnetic separation, jigging, hydrocyclones and spiral concentrators. The tailings from the process plant are generated from classifier overflow of 135 tons per hour dry solids and thickener underflow of 48 tons per hour dry solids. A systematic experimental program was carried out using Multi-gravity separator (MGS), and wet high-intensity magnetic separator (WHIMS) for recovering the iron values from both of the tailing streams while minimizing the total quantity of tailings to be discarded. The classifier overflow contained 32.3 percent iron, 49.9 percent silica and 2.18 percent alumina and was 45 percent finer than 45 microns in size. The thickener underflow sample contained 47.3 percent iron, 27.6 percent silica and 2.49 percent alumina and was 16 percent finer than 45 microns in size. Separation results on the classifier overflow sample with the MGS indicated that a concentrate containing 62.1 percent of iron, 10.8 percent silica and 0.36 percent alumina can be achieved with a weight recovery of 24.5 percent. The results with WHIMS at 6500 Gauss indicated that concentrate containing 62.6 percent iron, 8.3 percent silica, and 0.65 percent alumina can be achieved at a weight recovery of 34.7 percent. 4.7 percent. WHIMS studies at 6500 Gauss on thickener underflow sample indicated that a concentrate containing 61.4 percent iron, 8.8 percent silica, and 1.74 percent alumina can be achieved at a weight recovery of 57.2 percent. Based on these results, and further in-house test works, a WHIMS installation was adopted for the recovery of iron values from the tailings in the operating plant at ArcelorMittal Serra Azul Mines, Brazil.