Abstract
The effects of reduction temperature, gas linear velocity, reduction pressure, reduction time, and reducing gas on the fluidized ironmaking process were studied for the fine iron Newman ore particles (0.154–0.178 mm) and the optimal experimental operating conditions were obtained. Under the optimal conditions, the effects of the coated cow dung on the reduction of fine iron ore particles were studied, and the inhibition mechanism of cow dung on particle adhesion in the fluidized ironmaking process was elucidated. The experimental results show that the optimal operating parameters are linear velocity of 0.6 m/s, reduction pressure of 0.2 MPa, reduction temperature of 1023 K, H2 as the reducing gas, and reduction time of 60 min. Cow dung can react with oxide in the ore powder to form a high melting point substance that can form a certain isolation layer, inhibit the growth of iron whiskers, and improve the fluidization.
Highlights
Australian Newman ore was used for the reduced fine iron ore particles, and its chemical composition and scanning electron microscopy (SEM) image are shown in Table 1 and Figure 1, respectively
Because the bond loss of fine iron ore powder is affected by reduction temperature, reduction time, reduction pressure, linear velocity of reducing gas, and type of reducing gas, these factors are investigated from three aspects
To better study the effect of cow dung on the fluidization quality of fine iron ore particles, MgO, plastic particles (PP, PE, etc.) and carbon were selected to compare with cow dung and their contents were set to 5%, 10%, 15%, and 20%, respectively, in order to explore the influence of content on fluidization quality
Summary
The bonding of fine iron ore particles in the fluidized ironmaking process is complex and involves four bonding mechanisms, namely, the iron whisker bonding mechanism, the newly formed metal iron bonding mechanism, the low melting point eutectic bonding mechanism, and the van der Waals force and field bonding mechanism. Chironea et al [8,9,10] found that low-frequency and high-intensity acoustic and magnetic fields can induce ferromagnetic materials to form needle-like substances along the magnetic line of force in the bed, producing a crushing effect on the agglomeration force of newly precipitated iron agglomerates This hinders the growth of the newly precipitated metallic iron and effectively improves the fluidization performance of the particles and reduces the interparticle adhesion. These results provide an important scientific basis for the industrial application and development of a fluidized direct reduction process. The mechanism for the inhibition of the loss of adhesion of fine iron ore particles by cow dung was studied and elucidated, providing reference data and theoretical basis for industrial use of fluidized direct reduction
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