Papers by Keyword: Sintering Process

Abstract: In order to manufacture high-value added materials from steel slag, a steel slag-based ceramic was prepared in the paper. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were carried out to characterize the phase formation and the microstructure of the steel slag-based ceramics. Besides, the line shrinkage, flexural strength and water absorption were also determined.Results show that the variation of the line shrinkage and the flexural strength had a positive correlation with the increase of the temperature at the interval 1160°C~1210°C, which was opposite to the change of the water absorption. 1210°C was proved to be the optimum sintering temperature in this work, at which the maximum flexural strength was obtained with a value of 99.39MPa. With the temperature increasing, the quartz phase gradually decreased, participating in the sintering reaction, and the diopside become dominant phase with columnar crystals in 2-5μm at length, which would contribute to the fine performance of the ceramics.

Abstract: In this research, the Y123 (YBa₂Cu₃O_x) and Y134 (YBa₃Cu₄O_x) superconductors were synthesized by solid state reaction and melt process, respectively. The crystal structure of all the samples were then determined using the Rietveld full-profile analysis method to indicate orthorhombic structure. The resistivity measurements showing T_c onset of Y123 lower than Y134 for solid state reaction but higher than Y134 melt process. However, the critical temperature off-set of Y134 has lower than of Y123. The SEM and EDX show that all samples were inhomogeneous. The SEM micrograph for solid state reaction Y123 has many pores between the grain and the grain size clearly demonstrated and bigger than Y134. It was seen that these pores are party eliminated in melt process samples. FTIR spectra detected the trace of carbonate residue in all samples.

Abstract: Tunnel kiln was reformed according to energy-saving mode, which was energy utilization diagnosis and analysis and energy-saving reconstruction. First, thermal performance was diagnosed, and the basic data for energy-saving reconstruction was provided through the test of tunnel kiln. Then the main factors of low thermal efficiency was found .Second the thermal balance was calculated in drying and sintering process, which determined the form of waste heat recovery and utilization system. Finally the reconstruction was implemented by three energy-saving technologies .It caused energy-saving rate reached 44%.

Abstract: In this paper, the de-silicated fly ash (DSFA) was sintered with soda and calcium oxide. Detailed analysis and characterization was carried out by using thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). Two dominant reactions take place in the sintering process. The kinetics was studied by using Jander mode, and the sintering activation energies were determined based on the weight loss of CO_2.

Abstract: In this paper a new technology for a compact iron ore sintering machine is analyzed. The compact sintering process is based on the massive injection of gaseous fuels and the solid fuel is only agglomerated fine charcoal obtained by biomass. The solid fuel used in this study is obtained by agglomeration of fine charcoal produced from elephant glass which has very short period for production and CO₂ capture (less than 6 months in tropical climate). To overcome the lower heat supply into the combustion front of the sintering process the simultaneous injection of oxygen and gaseous fuel is proposed. The proposed methodology is to combine the solid fuel (agglomerated fines charcoal) and steelworks gases in a compact machine to enhance heat and mass transfer with high productivity (about 5 times the conventional large machine). A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is used to analyze the inner process parameters. A base case representing a possible actual industrial operation of the sintering machine is used in order to compare different scenarios of practicable operations which represents advanced operations techniques. The model was used to predict six cases of combined operation with biomass and fuel gas utilization: a) Scenario 01 and 02: Wind boxes inflow from N01-N10 of rich mixture of natural gas (NG) +Air +O₂, b) Scenario 03 and 04: Wind boxes inflow from N01-N10 of rich mixture of coke oven gas (COG)+Air + O₂, c) Scenario 05 and 06: Wind boxes inflow from N01-N10 of mixture of COG+BFG+Air+O₂. The model predictions indicated that for all cases, the sintering zone is enlarged and the solid fuel consumption is decreased. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution within a compact sintering machine (in this study was the scenario 05), which enhance the productivity keeping good inner temperature distribution which promotes formation of calcium ferrites of structural shape which confers adequate metallurgical properties for blast furnace sinter. This technology is also expected to decrease considerably the specific CO₂ emissions, as demonstrated by scenarios simulated. It worthy to mention that, although the solid fuel considered in this work is produced from biomass the gas utilization is attractive due to decrease of the CO₂ emissions and the gas mixtures can easily be obtained by using inner steelworks gas.

Abstract: Hercynite (FeAl₂O₄) with octahedral structure rarely exists in nature and can only be synthesized artificially. However, it is hard to synthesize high purity hercynite. To date, it is known that two main synthetic methods, sintering and electro-fusion processes, are available to synthesize hercynite. Specimens synthesized by the two processes are different in Microstructure and phase compositions. The variations are researched by SEM, XRD and EDS.

Abstract: This paper is focused on the numerical simulation of a new technology of small size iron ore sintering machine using gaseous fuel and oxygen injections to produce high quality of sinter product for the blast furnace operation. The proposed methodology is to partially replace the solid fuel (coke breeze) by steelworks gases in a compact machine to enhance heat and mass transfer. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is proposed to analyze the inner process parameters. A base case representing a possible actual industrial operation of the sintering machine is used in order to compare different scenarios of possible operations which represents advanced operations techniques. The model was used to predict four cases of fuel gas utilization: a) 3% of the wind boxes inflow from N01-N10 wind boxes of natural gas (NG) and oxygen, b) same condition with coke oven gas (COG) and c) mixture of 80% COG and 20% blast furnace gas (BFG). The model predictions indicated that for all cases, the sintering zone is enlarged and the solid fuel consumption is decreased about 12kg/t of sinter product for the best combination. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution within a compact sintering machine, which enhance the productivity and obviously, decrease the investment cost of the sintering facilities.

Abstract: Ti(C,N)-based cermets were fabricated by the vacuum hot-processing technique. The effect of sintering process, initial powder size and binder content on mechanical properties of Ti(C,N)-based cermets were investigated. The composite was analyzed by the observation of scanning electron microscope (SEM) and energy dispersive spectrometry (EDS). The results showed that a lower sintering temperature led to insufficient liquid-phase sintering process, which reduced the density of the composite. However, higher temperature and longer holding time resulted in abnormal grain growth, which was not good for improving the mechanical properties of the composite. With the refinement of the initial powder size of the Ti(C,N), the fracture toughness reduced slightly, the flexural strength and Vickers hardness increased. The better mechanical properties were obtained when the binder content of the cermets was designed based on the eutectic composition of Mo-Ni binary alloy phase diagram.

Abstract: PTFE/Al reactive material was prepared via a hot pressed sintering process and comparative experiments were conveyed considering heating rate, sintering temperature and heat preservation time. The internal microstructure of the material was investigated using metallurgical microscope and stereomicroscope. From the investigation the influence of process parameters of hot pressed sintering on the properties of the material were deduced, and the analysis was verified by testing the impact initiation property with drop hammer method. The density of the material was measured according to the Archimedean principle. and the results showed that the best operating conditions of these three factors are 80°C/h, 365°C, and 0.5h, This new method has a higher effectively (short process time) and need lower operation conditions (low sintering temperature and pressure) comparing with the traditional cold sintering process.

Abstract: In this research, we synthesized and characterized the physical properties of YBa₂Cu₃O_x (Y123) and YBa₄Cu₅O_x (Y145) superconductors by solid state reaction and melt process. The raw materials Y₂O₃, BaCO₃ and CuO were mixed, ground and react in the air atmosphere at 950 °C, at 980 °C for solid state reaction and melt process, respectively. The samples obtained were characterized by the resistivity measurement, SEM, EDX, XRD and DTA. It was found that the critical temperature onset of Y145 is 94 K and 96 K for solid state reaction and melt process, respectively. The samples were inhomogeneous with no impurity. The crystal structures was orthorhombic which a = 3.80446 Å, b = 3.86474 Å and c = 19.37104 Å for Y145 solid state reaction and a = 3.80180 Å, b = 3.86483 Å and c = 19.38194 Å for melt process. The peritectic temperature of Y145 is 1018 °C.