Estudo de novos coletores comerciais para flotação de itabiritos compactos

Abstract

Currently a small range of commercial collectors is available for the use in iron ore flotation at Vale. This input represents a considerable unit cost and is essential for the concentration of low-content itabirites. The present work evaluated the reverse cationic flotation of an itabirite ore with low iron content (39.6 % Fe) from the Iron Quadrangle in bench scale tests, focusing on the use of new reagents and sieving aid to remove coarse quartz. The study evaluated the performance of 10 new collectors from the etheramine family with different degrees of neutralization, investigating the use of specific collector dosages and, staged collector dosage (70% of the amine mass in the conditioning time and 30% during the collection of foam) and the use of a co-collector reagent. The other flotation process variables were set as industrially practiced at the Cauê plant. The concentrate of each test was sieved in a 0,150 mm to evaluate the undersize and oversize contents, simulating the quartz removal step in industrial high frequency sieving. In tests with specific collector dosage variation, the etheramines without a degree of neutralization showed better performance, with silica content in the concentrate lower than 4.5%, iron in the tailings lower than 23%, metallurgical recovery of up to 75 %, and Gaudin selectivity index between 5 and 10. The tests with staged amine dosage and also with the use of co-collector showed poorer results than the tests evaluating the specific dosage for all analyzed reagents, although the performance of the amines without neutralization degree was also superior. In the sieving tests, it was observed that quartz particles with a diameter greater than 0.150 mm present a low response to flotation, contaminating the concentrate. These results indicate the potential for the use of amines without a degree of neutralization industrially, in addition to a great potential for reducing operational flotation costs with the optimization of specific amine dosage and, above all, by reducing the amount of coarse quartz in the concentrate using high frequency sieving.