Effects of Multi-stage Grinding Process and Grinding Fineness on Desulfurization Separation of High-sulfurous Iron Ore

The complex disseminated relationship between pyrrhotite and magnetite as well as poor liberation of finely disseminated sulfurous pyrrhotite was revealed through the mineralogy investigation of certain high-sulfurous iron ore. Grinding process and fineness have been found as significant factors influencing the flotation desulfurization performance of high-sulfurous iron ore. Moreover, the separation tests of multi-stage grinding as well as direct one-stage fine grinding were conducted. The results show that desulfurization effect of the former is much better in comparison with the latter. For one thing, sliming losses and slime influences on the separation process were relieved when the separation process of multi-stage grinding was adopted. For another, the grinding circulating load was effectively reduced while the number of high quality particles was increased, which benefits the liberation of valuable minerals. In conclusion, a technological flowsheet was presented. As a first step, one-stage low intensity magnetic separation of mineral particles to produce rough concentrate of magnetic iron was applied under the condition of grinding fineness 65% -0.074 mm. The next step was a fine regrinding of the obtained rough concentrate to 90% -0.045 mm. In succession, an activation of ore pulp with combined activators, as well as a reverse flotation of pyrrhotite with combined collectors to produce magnetite concentrate was employed. The reverse flotation consisted of one-stage roughing, three stages of cleaning and one-stage scavenging. Lastly, another low intensity magnetic separation step on the obtained magnetite concentrate was applied to produce the final iron concentrate. The obtained iron concentrate reaches 64.28% Fe and 0.42% S respectively with iron recovery of 53.62% and desulfurization rate of up to 90%. Technical basis can be provided for the industrial desulfurization application of high-sulfurous iron ore due to the favorable separation efficiency.