FEATURES FORMATION ZONE OF WAVES AND BURSTS ON THE SURFACE LADLE BATH

The results studies influence physicochemical properties and thickness cover slag, formed during ladle desulfurization pig iron by blowing a mixture of lime and magnesium, features formation a breaker on the surface bath and the level of metal losses with emissions outside ladle from this zone are presented. The necessity creating conditions for ensuring height breaker, which would not exceed thickness slag layer on the surface bath, has been substantiated. Using results of the high-temperature simulation blowing the cast iron melt with a neutral gas supplied through the nozzles tips stationary and rotating submersible lances, features development of counter waves and metal splashes in the absence and during formation slag cover with thickness of 30—80 mm on the surface bath are determined. The features change in the height and area breakers are determined depending on the gas flow rate for blowing bath and thickness slag. Based on the analysis results low-temperature modeling bath blowing, scientific ideas about the combined effect of the bath blowing intensity, speed of rotation submerged lance and thickness slag layer on the diameter bubbling zone, gas saturation of the bath and features wave formation on its surface in the slag-free zone were further developed (so-called «eye»). The nature relationship between length of the gas jet from lance nozzle, diameter «eye», and geometric parameters breaker has been established. It is shown that dependence profile breaker on speed of rotation lance and thickness slag layer is nonlinear. So, blowing bath through tip of a rotating lance with one nozzle at 240 rpm. with a gas flow rate of 2.2 l/min. creates conditions for raising top breaker to a height that is 33 % higher than the current thickness slag layer and contributes to the intensification formation of waves and bursts on the surface bath. With a decrease in the gas flow rate to 1.0 l/min., Under other unchanged conditions, height breaker is already 2/3 of the height slag layer, and as thickness slag decreases proportionally decreases. The smallest, recorded in the experiments, relative height breaker was 33.3% of the slag thickness at a lance rotation speed in the range of 90—120 rpm. Mathematical models are proposed that are suitable for calculating height breakers depending on the thickness slag layer, speed of rotation lance and intensity of gas injection into the bath. Taking into account established mutually opposite effect thickness of the cover slag layer and speed of rotation submerged lance on the «eye» area and height of the breaker, it is advisable to continue search for ways to improve design tip submerged lance and slag mode of ladle desulfurization.

CFD Investigation of Rotational Sloshing Waves in a Top-Submerged-Lance Metal Bath

Computational fluid dynamics (CFD) is applied to investigate rotational sloshing waves in a top-submerged-lance (TSL) cylindrical metal bath. The study is an extension of a recent work of the authors, where the top injection of Ar into a metallic bath was examined in a quasi-2D flat setup, allowing the numerical model to be extensively validated against experimental data based on x-ray radiography. The new analysis of top gas injection in a cylindrical vessel reveals the appearance of rotational sloshing in the bath, which is maintained by a condition of synchronism between the gas bubbles and the free surface of the bath. A numerical quantification is achieved with specific post-processing of the simulation results, showing the effect of control parameters such as the lance immersion depth and the gas flow rate. This fundamental research study demonstrates the capability of CFD modeling to predict bath dynamics known from literature and practice, the understanding of which is essential for the design of TSL furnaces.

Effect of Lead and Antimony on Sulfuric Acid Leaching of Copper in Speiss from Top Submerged Lance Furnaces

Cu-Pb and Cu-Sb alloys were prepared at various ratios, from 10:90 to 90:10, and leaching tests with sulfuric acid were conducted to investigate the effect of Pb and Sb on the leaching of Cu from speiss, which is obtained from the top submerged lance furnace process. The Cu leaching efficiency increased as the amount of Cu increased in both alloys, but the leaching efficiencies were lower in the Cu-Sb alloy than in the Cu-Pb alloy. For example, in alloys with 70% Pb and Sb ratio, the leaching efficiency of Cu from the Cu-Pb alloy increased to 95%. The leaching efficiency of the Cu-Sb alloy was 67% in 2 mol/L sulfuric acid solution with 1% pulp density and 1000 cc/min O2 at 90 °C, 400 rpm, and 6 hours. When the leaching residues were examined with SEM (scanning electron microscopy)-EDS (Energy-dispersive X-ray spectroscopy), it was found that in all Cu-Pb alloys, Cu and Pb exist as independent metal phases, while, in Cu-Sb alloys, Cu formed intermetallic compounds with Sb such as Cu2Sb, because the Cu-Sb alloy has a lower melting point than the Cu-Pb alloy. These results suggest that Sb may retard the leaching rate of Cu from the alloy. When the leaching residue of speiss obtained from a top submerged lance furnace, intermetallic alloys of Cu-Sb were also observed, having a net structure. The net structure contains Cu metal in the center of the speiss particle, while the intermetallic alloys of Cu-Sb were present in the outer layer of the particle, in good agreement with the results using the alloys in this study. This suggests the intermetallic alloys of Cu-Sb can prevent copper from leaching.

Hydrochloric Acid Leaching Behaviors of Copper and Antimony in Speiss Obtained from Top Submerged Lance Furnace

Copper (Cu) has been recovered from speiss generated from top submerged lance furnace process, but it was reported that the leaching efficiency of Cu in sulfuric acid solution decreased with increasing antimony (Sb) content in the speiss. Scanning electron microscopy (SEM)–energy-dispersive X-ray spectroscopy (EDS) results indicate that Sb exists as CuSb alloy, which would retard the leaching of Cu. Therefore, hydrochloric acid leaching with aeration was performed to investigate the leaching behaviors of copper and antimony. The leaching efficiency of Cu increased with increasing agitation speed, temperature, HCl concentration, and the introduction ratio of O2, but also with decreasing pulp density. The leaching efficiency of Cu increased to more than 99% within 60 min in 1 mol/L HCl solution at 600 rpm and 90 °C with 10 g/L pulp density and 1000 cc/min O2. The leaching efficiency of Sb increased and then decreased in all 1 mol/L HCl leaching tests, and precipitate was observed in the leach solution, which was determined to be SbOCl or Sb2O3 by XRD analyses. However, in 2 mol/L–5 mol/L HCl solutions, the leaching efficiency of Sb increased to more than 95% (about 900 mg/L) and remained, so more than 2 mol/L HCl could stabilize Sb ion in the HCl solution.