Reavaliação de circuito de flotação convencional de minério de ferro

Abstract

Samarco Mineração, since the start up in 1977 at Germanos mine, has been a pioneer in mining and beneficiation of low grade friable iron ore (itabirite). Currently the decrease in iron content and increase in contaminants grade, associated with greater participation of compact and semi-compact materials, has impacted the recovery of concentrator I conventional flotation circuit. The recovery reduction in the flotation stage motivated the current flotation circuit reevaluation seeking alternatives to restore the recovery without affecting the final concentrate content with low investment. Sampling, physical, and chemical characterization of samples, bench scale flotation tests and mass balance were conducted. Analysis of the results showed opportunities to improve the circuit performance. The stages prior to the flotation circuit change were: rougher, cleaner, recleaner and scavenger. After the circuit reevaluation, the recleaner was transformed into cleaner scavenger. Prior to the modification the iron grade in the scavenger concentrate was 24.26%, representing 38% of the new feed. With the circuit modification, the circulating load was reduced from 38% to 10% and the iron content increased to 48.8%, resulting in increased residence time. The iron content in the global tailings was decreased from 10.92 % to 6.36% representing gains in both mass and metallurgical recoveries.