Advanced Materials Research Vols. 881-883

Abstract: The characteristics of the Sierra Leone iron ore were studied at laboratory scale by chemical analysis, XRD, SEM-EDS and TG-DSC methods. The Sierra Leone iron ore was a kind of limonite, which was mainly consisted of hematite, goethite and gibbsite. The iron ore lost its crystal water at a fast speed ranging from 200°C to 400°C and the total content of the crystal water was about 8.2 wt.%. The initial melt formation temperature of the iron ore with CaO was stably kept at around 1209°C and the amount of liquid increased with the increasing of CaO content. Its melt formation temperature is higher than Australian limonite. The sintering pot test showed that the yield of sinter decreases from 78.37wt.% to 73.36wt.% and the drum index decreases from 60.5wt.% to 49.63wt.% when the blending ratio of Sierra Leone iron ore increases from 7wt.% to 27.3wt.%.

Abstract: The nonlinear isoconversional method has been applied to data for nonisothermal thermal decomposition of calcium carbonate. It is shown that the dependence derived from nonisothermal data can reveal the complexity of solid reaction. Therefore, the nonlinear isoconversional method is recommended as a trustworthy way of obtaining the activation energy of solid reaction under nonisothermal conditions.

Abstract: Abstract. The microwave energy absorption of solid mineral in microwave field is the key problem of the microwave metallurgy application. For the calculation formula of absorbing microwave energy (P=2πfε₀ε"E²) the fundamental data is necessary, including dielectric constant and electric field strength etc. But these basic data varies in practice due to the variation of molecular structure, overall dimension, and electromagnetic parameter of the mineral. Therefore, the theoretical calculation formula is difficult to predict the microwave absorbing ability of solid mineral [1-3]. In this paper the ability of four kinds of sulphide concentrate and their mixture coupling in absorbing microwave was investigated by intermediate medium calorimetry. The results show that the microwave-absorbing ability of chalcopyrite concentrate is the strongest, sphalerite concentrate is the weakest, and sphalerite concentrate is stronger than silica, the mixture minerals still keep their own microwave absorbing characteristics. The mass percent of strong absorbent of microwave decide the microwave-absorbing ability of mixture, and affect energy transfer between microwave and mineral.

Abstract: The application of microwave technique in the roasting pyrite which contained little arsenic was described. The characteristics of microwave absorption of pyrite were investigated. The results indicated that pyrite was a good absorbent of microwave and heated rapidly to high temperature by microwave flied in a short time, causing decomposition and oxidization to removal the sulfur and arsenic. The effects of microwave irradiation time and sample mass on the removal efficiencies of sulfur and arsenic with microwave power of 4 kW and 6 kW were investigated. The big microwave power could shorten the time for removal of sulfur and arsenic. Finally iron concentrate contained 64.52% Fe, S<0.1%, As<0.094% were obtained.

Abstract: Through using jiuquan bituminous coal, yangquan anthracite, coking coal and charcoal as fuel,under 900 °C simulating the preheat layer of sinter process,research the influence of fuel types and content on gasification dephosphorization.Results show that due to the different volatile matter of coal, the influence on gasification dephosphorization is different, the influence of the highest volatile bituminous coal to the dephosphorization effect is best when carbon content takes 4%.

Abstract: The integrated technology of oxygen blowing and bottom blowing was the core of EAF combined-blowing. Today's process model can not exactly describe the control of combined-blowing. In this paper, the EAF steelmaking history data was analyzed by K-medoids clustering algorithm which is data mining technology. Different clustering results were obtained under the cost of steelmaking, oxygen consumption, and etc. Finally, the optimizing combined-blowing curve is found out by analyzing the classified results. In the early of smelting, the flow rate of No.1 oxygen lance and No.2 oxygen lance is increased to improve the strength of decarburization and the pace of smelting. In the late of smelting, door oxygen lance starts to be used for dynamics conditions of carbon-oxygen reaction. The two bottom blowing lance use argon instead of nitrogen after 21 minutes in order to protect the steel components.

Abstract: The dissolution kinetic of Na_xH_2-xTiO₃ (resulting from high titanium slag treatment by NaOH) by diluted sulfuric acid (38~51 wt. %) was carried out in temperature range of 10 to 50°C with an initial acid/Na_xH_2-xTiO₃ (wt.) ratio of 1:1. The effects of the sulfuric acid concentration and temperature on titanium dissolution percent were reported, and both of them significantly affected the dissolution rate. The experimental data indicate that the shrinking core model controlled by diffusion in product layer is most applicable for the titanium dissolution process, and the apparent activation energy has been estimated to be 28.69 kJ/mol.

Abstract: In the bacterial leaching, the oxidation of Fe²⁺ is very important process. According to the results of this paper, Fe²⁺ and Fe³⁺ concentration effect on the growth of moderate thermophile. The optimum conditions for growth of moderate thermophile are the initial concentration of Fe²⁺ at 0.16mol/l. It indicates the existence of the optimum conditions including initial concentrations of Fe²⁺ and Fe³⁺ for the bio-oxidation Fe²⁺. To increase the initial concentration of Fe³⁺ can enhance the oxidation rate of Fe²⁺. The dynamic model of the moderate thermophile oxidation Fe²⁺ has been established by analyzing and calculating test data with the Matlab software.

Abstract: In this study, the dissolution effect of zinc oxide ore was investigated using sulfamic acid solution as leaching agent. The effects of temperature, concentration of sulfamic acid, average particle size and stirring speed on the dissolution of zinc oxide ore were investigated. The dissolution rate increased with increasing solution temperature, concentration, and stirring speed as well as with decreasing average particle size. Sulfamic acid solution can therefore be used as an effective leaching agent for zinc extraction from zinc oxide ore.

Abstract: In this paper, a two-dimensional non-steady-state heat transfer model has been established for the working conditions of thick slab in a steel plant in China, a modification has been made on the basis of the nailing experimental results, the slab solidification difference of practice and prediction by field heat tracing model has been analyzed. The results show that the actual solidification end point of slab is more close to meniscus than prediction, the distance difference is 0.592m, the better soft reduction zone is from 0.2 to 0.9, which the level of central segregation can be reduced from the class B 1.0 to C 1.0.