Novel-modified magnetic multi-walled carbon nanotubes (MMWCNTs) were synthesized via evaporating acid purification and co-precipitation method. MMWCNTs were used for simultaneously removing lead and zinc ions from aqueous solutions. Transmission electron microscope, field emission scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), and magnetization curve showed the morphology, composition, surface functional groups, and magnetic properties of MMWCNTs. Then, the adsorption effects were investigated by times, pH, and adsorbent dosages. The results showed that Fe₃O₄ of approximate 10 nm successfully grafted on the surface of MWCNTs. The results of XRD, energy-dispersive X-ray spectroscopy, and XPS further confirmed that the iron oxides were Fe₃O₄. Adsorption data were analyzed with Lagergren pseudo-first-order, pseudo-second-order kinetic, intraparticle diffusion, and liquid film diffusion models. Langmuir isotherm model showed the maximum adsorption capacities as 67.25 and 3.759 mg/g for lead and zinc ions, respectively. These results indicated that MMWCNTs may be a promising candidate for removing heavy metal ions from aqueous solutions.

A transient two-dimensional mathematical model is developed to study the influence of fuel type and operation parameters on combustion and NO_x emission during the iron ore sintering process. The model was validated by comparing the model predictions with sintering pot test data. The predictions show reasonable agreement with the averaged values of the test data. In addition to the conventional sintering process, this model can also predict new processes such as flue gas recirculation, gas fuel injection, and fuel layered distribution. The simulation results show that the fuel NO_x is the main part of the NO_x emission during sintering, and thermal NO_x forms a very little part. The produced NO_x can be reduced not only by coke but also by CO around coke particles, with reduction proportions of 50% and 10%, respectively. Two types of coke A and B were compared. With Coke A as solid fuel and consumption of 3.8%, the NO_x emission was 320 ppm. Increasing the replacement of Coke A with Coke B, the NO_x emission was decreased, being decreased by 28.13% to 230 ppm with the replacement proportion of 50%. When only Coke B was used, the NO_x emissions could be lowered by 53.13% to 150 ppm. Decreasing the particle size from 1.6 mm to 1.2 mm led the NO_x emission to be increased by 10.93% from 320 ppm to 355 ppm. With Coke A as the only solid fuel, increasing the fuel ratio to 4.2% led the NO_x emission to be increased by 9.38% to 350 ppm; increasing the oxygen content of inlet air from 21% to 30% led the NO_x emission to be increased by 15.00% from 320 ppm to 368 ppm.

The Kanbara Reactor (KR) is a primary desulfurization technology in the hot metal pretreatment refining process that is widely employed in the modern steelmaking industry. The operating parameters of KR impeller immersion depth (IID) and rotation speed (IRS) have a crucial impact on the process performance and the desulfurization effect. Still, their influences have not been fully understood. This study systematically investigated the effects of IID and IRS on the flow pattern, mixing behavior, vortex core depth, and free surface characteristics for KR processes based on a 3D Volume of Fluid (VOF) model coupled with the sliding mesh method (SMM). The model was validated via scale-down water model experiments and then applied to the KR process, and simulations found that IID and IRS have different impacts on the flow pattern. Specifically, the discharge flow location moves downward with IID increasing, but the discharge strength and mean velocity hardly changes. Comparatively, the rise of IRS significantly increases the mean velocity, but few changes occur to the discharge flow position. Increasing IRS improves bath hydrodynamics, strengthens recirculation, and efficiently shortens mixing time, but IID has a neglectable effect on these features. The minimum mixing time is 55 s at a maximum IRS of 260 rpm. Moreover, the vortex core depth and free surface velocity visibly increase with the increase of IRS. Comparatively, IID has a limited effect on the flow and mixing behavior but directly impacts the distribution of recirculation regions at the axial direction and the velocity gradient on the free surface at the radial direction. Furthermore, the correlation equations of these critical parameters as a function of the operating parameters were obtained. The results from this study may provide references for operating optimizations and industrial practices of KRs.

The slag behaviors, directly relating with the qualities of the final cast products, are influenced by the transient surface flow of liquid steel in a continuous casting mold. A one-half scale model is used to investigate the slag behaviors and their droplets entrainment. The model based on Volume of Fluid (VOF) multiphase coupled with Large Eddy Simulation (LES) is established to further illuminate the phenomena of the liquid oil layer fluctuation, the slag “eye” regions, and the slag entrainment observed in water experiment. The effects of casting speeds on the slag behaviors and their entrained droplets are investigated. The results show that the fluctuation of the oil layer is influenced by the transient flow. The calculations for the oil layer profile, the accumulation, and protrusions of oil layer are consistent with the water experiment. The asymmetry of the slag “eye” regions is also influenced by the asymmetry of free surface and transient turbulent flow. The “eye” regions near the narrow wall show distinct asymmetric change at different casting speeds. At a lower casting speed, the slag “eye” regions change irregularly and display the alternate process of open and collapse at the two sides of the narrow walls of the model. While at a relative higher casting speed, the slag layer gathers toward the nozzle, and the slag “eye” regions gradually grow and always open. The simulation model can reveal that the mechanism of the slag entrainment includes two main modes: the cutting or dragging mode and shear layer instability. The average diameter and amount of the entrained droplets are calculated through the UDF codes of ANSYS FLUENT software, and the size distribution of the entrained droplets is also counted. When the casting speed is lower, the dominant diameters of the entrained droplets range between 2 and 3 mm. With casting speed increase, the distribution of the droplets becomes wider, and there is a gradually increase in the percentage of larger droplets with a size of 4–6 mm.