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.
To improve the fluidization of the fluidized bed in ironmaking, the particle loss and bonding during the fluidized bed are largely removed by changing the properties of the particle surface or by adding an external field. Currently, the vibration, magnetic, sound, and electric fields have been commonly applied to provide external energy to the fluidization bed systems. In this work, experiments are conducted for Newman ore particles under the application of an external sound field at a reduction temperature of 1023 K, linear velocity of 0.6 m/s, duration of 60 min, pressure of 0.2 MPa, and typical mineral powder particle size of 80–100 mesh, with H2 used as the reducing gas. The power and frequency of the ultrasonic field are varied, and the effects of sound field are evaluated by the comparative analysis of the effects of the sound field with different powers of sound fields and application times on the metallization rate and binder ratio of the samples. The acoustic pressure and frequency were varied to determine the critical speed and influence on the bed and to study the interactions of the iron ore powder particles in the sound field and the bonding mechanism of the particles. The results of this paper reproduce the actual particle fluidization process and analysis of the interactions of the particles in the sound field well. The influence of the external sound field on the gas-solid flow was studied from the perspective of macroscopic motion and force analysis.
The maximum current density (jmax) is of importance to the modeling of current produced in a bioelectrochemical system (BES). This study explores an alternative to biomass and biofilm thickness, the accumulated charge density (τ) of electroactive bacteria on the bioanode, to estimate the jmax value. The τ values of five carbon‐based bioanodes are chronoamperometrically determined in a substrate‐depleted solution. The graphite felt bioanode acclimated for 1, 2, 4, and 6 batches exhibits τ values of 6.14, 11.80, 22.23, and 30.24 C m−2, respectively, and jmax values of 5.31, 6.69, 14.01, and 19.62 A m−2, respectively. A linear correlation between τ and jmax is achieved and can be expressed as jmax=0.64τ. The τ and jmax values of four other carbon‐based bioanodes also follow a linear relationship, with coefficients of approximately 0.64. These results imply that τ is a key parameter for estimating jmax in the BES without the need to determine biomass and biofilm thickness.
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