Abstract: There are a number of small sized magnetite ore concentrators in a region in Shanxi, which produce iron concentrates by low intensity magnetic separation that have an iron grade of only 61%～58% but an SiO₂ content as high as 12%～15%, not conforming to the guideline of good burden preparation for blast furnace iron-making and seriously affecting their sales. Based on the experimental research and in light of the local real conditions, a separate concentrator for their upgrading has been designed and built for a centralized treatment of these iron concentrates, which adopts a process consisting of reverse flotation, middling regrinding and low magnetic separation, and a high efficient anionic collector LP-4 that can be used in normal temperature. Now, this separate concentrator is running stably and has a good adaptability. It is capable to raise the iron grade of the concentrate to 67.2%～66.5%and reduce the SiO₂ content to 5.2%～5.8%, demonstrating a good effect of quality improvement and impurity reduction.

Key words: Iron concentrates of low intensity magnetic separation, Quality improvement and impurities reduction, Separate upgrading concentrator, Reverse flotastion, High efficient collector LP-4