Abstract
The oxidation roasting of vanadium–titanium magnetite (VTM) pellets with a new composite binder was investigated using a pilot-scale straight-grate. The evolution of the chemical and phase composition, the compressive strength, and the metallurgical properties of the fired VTM pellets were investigated. Under a preheating temperature of 950 ∘C, a preheating time of 18 min, a firing temperature of 1300 ∘C, and a firing time of 10 min, the compressive strength of the fired pellets was as high as 2344 N per pellet. The fired pellets mainly consisted of hematite, pseudobrookite, spinel and olivine. The total iron content of the fired pellets was 0.97% higher using 0.75 wt% humic acid (HA) binder instead of 1.5 wt% bentonite binder. These properties are beneficial for the production efficiency and energy efficiency of their subsequent use in blast furnaces. Moreover, both the softening interval and the softening melting interval of the HA binder pellets were narrower than those of the bentonite binder pellets, conducive to the smooth and successful smelting of the VTM pellets in a blast furnace.
Highlights
Pelletizing is one of the most important agglomeration processes for producing highquality, structurally sound, and metallurgically sound feed for blast furnaces and direct reduction [1]
The physical and chemical properties of the fired vanadium–titanium magnetite pellets during the straight-grate oxidization process were investigated based on the pilotscale operating conditions
For each pilot-scale experiment, 30 kg vanadium–titanium magnetite (VTM) concentrate was thoroughly mixed with a set amount of bentonite (1.50 wt%) or humic acid (HA) binder (0.75 wt%)
Summary
Pelletizing is one of the most important agglomeration processes for producing highquality, structurally sound, and metallurgically sound feed for blast furnaces and direct reduction [1]. Organic binders have not been widely used in China because the compression strength of the resulting preheated and fired pellets is insufficient and does not meet the requirements of grate-kiln processes. Pellet production by direct reduction has been achieved using this composite humic acid-based binder It has not yet been used in the industrial production of oxidized pellets. This study is a first attempt to apply a humic acid binder in oxidation roasting of vanadiumtitanium magnetite (VTM) pellets, via the straight-grate process, with the aim of exploring the optimal operating conditions for the drying, preheating, and firing of the pellets. The physical and chemical properties of the fired vanadium–titanium magnetite pellets during the straight-grate oxidization process were investigated based on the pilotscale operating conditions
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