Advanced Materials Research Vols. 785-786

Abstract: The microstructure and sintering properties of electrolytic manganese residue were investigated in this paper. The XRD results show that the manganese residue primarily consists of quartz (SiO₂) and chemical gypsum (CaSO₄·2H₂O). The crystal phase and structure of gypsum will transform at 107.4, 144.5, 483.2, 901.3 and 1093.5°C, respectively. When sintered from 880 to 940°C, the water–absorption (Wa) and porosity (Pa) of the sintered compact gradually increased, while the bulk density (D) and bending strength decreased instead. Once heated at 940–980°C, both Wa and Pa gradually decreased, but D and bending strength increased rapidly. The SEM observation of fractured surface shows that a number of pores appear at the sample’s interior. The corresponding changes of water absorption, porosity, densification and bending strength of the samples are closely linked to the occurrence of liquid phase inside the sintered compact.

Abstract: Ilmenite phase is complex in Shaanxi.There are mainly magnetite, limonite and ilmenite, and associated with extremely small amount of rutile. According to the occurrence iron and titanium in the ilmenite ore。Paper discussed comprehensive recycling of the ilmenite using wet low-intensity magnetic separation by stage grinding process . The results show that it obtains better mineral processing indexes。The productivity of ilmenite concentrate was 28.83%, the grade of iron in concentrate was 62.05%, the content of titanium was 13.11%, iron recovery was 61.73%, titanium recovery was 43.40%.

Abstract: The cordierite was synthesized at relatively low temperature by pressureless sintering method, using calcined bauxite, talcum , quartz and feldspar as raw materials in this paper. The water absorption (Wa), porosity (Pa), bulk density (D_b) and bending strength of samples have been tested, and the synthetic process and mechanism have been investigated by XRD, SEM, and so on. The results showed that the cordierite could be synthesized at 1280°C and the range of synthetic temperature is 1160~1300°C, when the sample was sintered at 1280°C for 2h, its bulk density and bending strength were 2.20g/cm³ and 72.13MPa, respectively. XRD analysis showed that the main phase of sample was cordierite, the cordierite content was about 88wt%, and the minor phases were MgAl₂O₄ spinel and corundum. SEM results showed that the samples were dense and the pore sizes were 5 μm~100μm, the grains were growth and development well, the grains size were 0.5μm~6μm. High reaction activity corundum and mullite were provided by calcined bauxite, then coupled with the role of feldspar, thus reduced the synthetic temperature of cordierite.

Abstract: How to effectively use high iron bauxites to alleviate the shortage of bauxite resources has become an hot topic in China. According to the technological characteristics, the method of comprehensive utilization of high iron bauxites can be included: first iron then aluminum, first aluminum then iron and simultaneous recycling iron and aluminum. This paper will review the research progress on the comprehensive utilization of high iron bauxites.

Abstract: The effects of refractory zinc oxide ore which came from Lanping of Yunnan Province were studied using agitation leach method in laboratory in order to find out the optimum leaching conditions. The optimum conditions obtained are as follows: ammonia concentration 3mol/L, ammonium bicarbonate 1.5mol/L, granularity (-0.074mm) about 85%, solid to liquid ratio 4:1, and leaching time 2h. On this condition, the test obtained the better index of the zinc leaching rate 74.4%.

Abstract: The temperature field and stress field were simulated using the finite element software (ABAQUS) for Q345c continuous casting slab during cooling process. The hot ductility curve, high temperature tensile strength curve, and the surface stress value were obtained according to thermal simulation experiments. The results show that the temperature of brittleness zone is at 600-850°C, and the value of surface stress is larger than the high temperature tensile strength in the slab cooling process. The heat insulation device should be installed between the flame cutting machine and the heating furnace to avoid hot crack defects caused by excessive thermal stress on the surface in the process of hot slab delivery.

Abstract: Leaching test on the Oxidized Zinc Ore coming from Yunnan Province is studied in the H₂SO₄ system;Systematic studies are made to show the effects of various factors on the leaching rate of zinc. The optimum conditions for leaching is finally confirmed, namely the grinding size is 75% of-0.074mm, concentration of sulfuric acid 15%, temperature 60°C, solid to liquid ratio 3:1, and leaching time 2.5h. Ultimately, the leaching rate of Zn could reach more than 59%.

Abstract: 2024 al alloy and Az31B Mg alloy joint by stirring brazing without flux in air. The microstructure and mechanical character of the interface were investigated. The results show that the maximum shear strength of the Al interface can up to 58.7Mpa and 37.5Mpa to Mg interface.

Abstract: Liquid metal flow behavior in round strands continuous casting under intermittently reversing direction electromagnetic stirring was measured by ultrasonic Doppler velocity-meter in a physical simulation system in order to investigate the effects of time interval () of periodically reversed magnetic field on the spatial and temporal flow. The results show that under electromagnetic stirring with direction reserved magnetic field, theres a periodically change of the metal flow velocity and rotation direction with the periodically direction changing of the magnetic field. From both the experimental and mathematical model calculation results, it is found that when is nearly equal to the time required for the metal flow speeding to the maximum velocity from still and decreases to zero again, there is a critical value of the rate of dynamic pressure, which means the wash effect of the liquid metal flow. On this point, rate of dynamic pressure was proposed to be a criterion for optimization the processing of electromagnetic stirring.

Abstract: There are two reasons to causes of defects of acid rolling line equipment and hot-rolled raw materials problems, so it is necessary to analyse the cold-rolled strip surface foreign body pressed into the defect microstructure and composition. It is found that this defect can be eliminated by improving the quality of the raw material, controlling strip shape, making reasonable squeezed roll transformation system, making the implementation of effective management of the full range of roll surface, carrying out the whole process of clean production, effectively controlling of the cold-rolled strip foreign body pressed into the generation of defects.