Advanced Materials Research Vol. 402

Abstract: Combining with the chemical reaction mechanism of sintering flue gas desulphurization with ferromanganese ore slurry, the effect of several technology parameters on desulphurization efficiency of simulative sintering flue gas was studied systematically with the sprayed bubbling reactor designed by ourselves. Result indicated that the desulphurization efficiency of sintering flue gas increased with the decreasing of ferromanganese ore particle size and the increasing of stirring speed of ferromanganese ore slurry. The high SO₂ concentration in sintering flue gas is not beneficial to improve the desulphurization effect. High desulphurization efficiency can be achieved by reducing flux of sintering flue gas. However, the formation of bubbling reaction is difficult if the sintering flue gas flow is too low, and then the desulphurization efficiency decreased.

Abstract: Stirring characteristics of wall oxygen lances of EAF and bath mixing under different conditions were studied by using an 1/10 length scale down of cold model of 100-ton capacity EAF. The effects of horizontal angle, vertical angle of a lance and the distribution of lances along the EAF wall on bath stirring and mixing were researched experimentally. The results showed that the horizontal angle of the lances had significant impact on the local fluid flow and mixing time, whereas the mixing time is less affected by the lance vertical angle relatively. It was found that the shortest mixing time had been obtained in the conditions that the horizontal angles were -3°, 0° and -2° respectively under the modified lance distribution in the variant shape of bath. Compared with the mixing time measured in the conditions of the prototype, the average mixing time for p1, p2 and p3 and the mixing time for p4 point were reduced by 52.3% and 44.7% respectively with the optimum scheme.

Abstract: The quality of continuously casting steel is greatly influenced by turbulent flow in the mold. Understanding the unsteady flow structures in this process is an important step in avoiding failures and decreasing defects. The cassette filter function is used to deal with unsteady Navier-Stokes equation, and then the turbulent flows in the thin slab continuous casting processes are simulated with the large eddy simulation (LES) method with the Smagorinsky sub-grid scale model. Characteristics of the unsteady turbulent flow in the thin slab continuous casting processes are exhibited. The turbulent asymmetric distribution was revealed even the nozzle in the centre position. And the vortices are located at the low velocity side adjacent to the nozzle.

Abstract: According to the assumption of local thermal non-equilibrium and the heat transfer controlled regime, a mathematical model describing the coupling between the heat and mass transfer processes in a porous packed bed with endothermic chemical reactions was established and solved by the alternate dimension implicit method. The calculated results showed that, the profiles of the temperature distributions of the two phases and the solid conversion ratio all decay near the radial boundary wall corresponding to the momentum boundary layer. However, the concentration of the product gas increases near the wall owing to the slower speed layer. The temperatures difference between the gas flow and solid pellets can not be ignored during the study of ore decomposition in the porous packed bed. The reaction features of the packed bed with endothermic reactions under different conditions can be analyzed by the established model.

Abstract: Polycyclic aromatic hydrocarbons (PAHs) is a kind of the typical persistent organic pollutants with their teratogenic, carcinogenetic, mutagenic. Coking production process has become one of the main sources of PAHs in the environment. For researching the generation and emission properties of PAHs in coking process, the writer studied the PAHs in single coal coking process through laboratory sampling and high-performance liquid chromatography analysis, observed and summarized the generation regularity and emission characteristics of PAHs in three kinds of single coal coking process, and provided the foundation data for the control of PAHs in coking process.

Abstract: The hot experiment was carried out to study the effect of lance nozzle and mixing gas blowing on steelmaking. The heat load of oxygen lance, component in the bath and dust generation were studied in the hot experiment under different lances and mixing blowing process. The absorbed heat is lower and the slag adhesion on the oxygen lance is reduced with the lance nozzle angle increasing. By using small portion of carbon dioxide as top gas is help to reduce the temperature in the impact area and decrease the dust generation, but the decarbonization rate decrease with the proportion of carbon dioxide increasing.

Abstract: The mechanism of a novel desulfurization method using spent Zn-MnO₂ batteries has been studied by X-ray diffraction(XRD), scanning electronic microscopy (SEM), energy dispersive spectrometry (EDS) and the experiments of SO₂ absorption. The XRD results show that the positive electrode of spent Zn-MnO₂ batteries consists of a mixture of α-MnO₂, Mn₂O₃ and Mn₃O₄ phase. The SEM results show that micropores and microparticles are observed in the positive electrode surface, the relative content of zinc and graphite increases in the positive electrode after discharging according to EDS. The results of absorption experiments show that the electrolyte of spent batteries is of weak alkali which verifies the feasibility of absorbing SO₂ using spent Zn-MnO₂ batteries. Furthermore, the solution obtained by washing the positive electrode with low concentration ammonia is of much better desulfurization efficiency than that with distilled water directly, and 40°C is the optimum to absorb SO₂ at a range of 30-70°C.

Abstract: It’s of great importance to innocuity, minimization and reutilization of manganese slag generated in manganese product by electric furnace process. In the paper, ordinary Portland cement was incorporated by manganese slag, and then mechanical tests were performed to obtain the fundamental properties of the cement stabilized material in order to analyze the road performance of cement stabilized layer. The obtained experimental results showed that the manganese slag cement replaced by 2~6%( wt) manganese slag has better road performance such as mechanical properties, hydro-abrasive erosion and chemical corrosion resistance.

Abstract: The effect of excess air ratio on combustion performance in an industrial furnace with a swirling burner was numerically modeled. The simulation was carried out at inlet oxygen fraction of 8% and a preheated air temperature of 1273 K for natural gas. The gas combustion process was calculated by a Beta function PDF (Probability Density Function) combustion model. The transportation of the turbulent flow in the furnace was modeled by Reynolds Stress Model (RSM). The radiation was simulated by a Discrete Ordinates method. The NO chemistry was simulated by thermal NO model. The effect of excess air ratio on NO emission, temperature, O₂ and CO distribution in the furnace was investigated. Results showed that thermal NO emission increased from about 5 ppm to 70 ppm when the excess air ratio increased from 1.05 to 1.25. The burnout of natural gas was improved at increased excess air ratio, i.e., CO emission decreased. The maximum and average temperature in furnace did not change much at different excess air ratio. When the excess air ration is 1.1, both good burnout of fuel and low thermal NO emission (<15 ppm) were achieved.

Abstract: Drying is a crucial step in the process of copper powder flash smelting for the direct influences on the quality of smelting. This paper proposes a unique system to match the special requirements of drying raw copper powder, such as large mass rate, small diameter dust and abrasion. On the bases of drying features and energy conservation, optimization design of drying system and equipment was also carried out. In site tests showed the satisfaction on working stability, energy thrift and quality of final product.