The study of pelletizing of mixed hematite and magnetite ores

Abstract

The present study aims to investigate the use of mixed hematite and magnetite ores in iron ore pellet production. Pelletizing tests were carried out on the hematite and magnetite premixed pellet feed. Drop number and compressive strength tests for green and dry pellets; porosity, compressive strength and reducibility tests for fired pellets were carried out to determine the influence of mixing ratios of both iron oxides on those pellet properties. Experimental results showed that as the hematite content in the mix pellets is increased, the green drop number decreased from 6.5 to 5.2, the green compressive strength decreased from 1.51 to 1.28 kg/pellet and the dry compressive strength decreased from 2.50 to 1.60 kg/pellet. It was determined that fired compressive strength of mix pellets decreased from 380 to 230 kg/pellet when the hematite content in the mixed pellet is increased. The reducibility of mix pellets had almost the same trend and it was faster up to 40 min reduction time. The results showed that the use of hematite together with magnetite is possible to produce pellets with sufficiently good quality in terms of wet, dry and fired mechanical strengths. The porosity and reducibility values of mix pellets were also found to be adequate to use as feed for the blast furnace.

Characterization of Magnetic Tailings from Phosphate-Ore Processing in Alto Paranaíba

“…Despite the advantages of magnetite in steel processes (sintering and pelletizing) and the fact that it is technically possible to chemically guarantee this waste's use by the steel industry, its processing is rendered unfeasible by the large hematitic iron ore reserves still dominating the steel market [16][17][18] . Moreover, studies that quantify magnetite formation in ore pellets in hardening furnaces at high temperatures, found that it reduces the produced pellets resistance, thus further undermining its use by the steel industry [19][20][21][22][23][24] .…”