Modification of mineral processing circuit in Arjin mine through a mineralogical study: magnetic separation and reverse flotation

The current mineral processing circuit of the Arjin iron mine faces serious problems regarding its reduced efficiency. In the present research, the concentrator circuit of the Arjin mine was modified through mineralogical study and other laboratory approaches magnetic separation, and flotation tests. The results verified that the feed contained magnetite as a valuable mineral with a degree of liberation of about 91 μm. The magnetic separation and flotation tests were conducted to modify the circuit by measuring the iron recovery, sulfur, and iron contents in the obtained concentrates and tails. The magnetic separation tests with a magnetic field strength of 1000 Gauss were carried out on the initial feed with different d80 to determine the influence of particle size. The results verified that the feed with d80 = 120 μm could be considered the best feed size for magnetic separation. The sulfur content was then reduced from 0.99% to 0.05% in the final concentrate of reverse flotation as a desulfurization step. Based on the results, the proper circuit included reverse flotation and magnetic separation consisting of rougher, cleaner, and re-cleaner with the field intensities of 2500 G in the rougher and 800 G in the cleaner and re-cleaner steps. Finally, the total iron content was improved from 58% to 68.1%, and the recovery percentage was raised from 65% to 83.39% by the applied modifications.