Papers by Keyword: Reduction Temperature

Abstract: The possibility of joint solid-phase reduction of iron and phosphorus from ferromanganese ore has been experimentally confirmed. Solid-phase reduction was performed at a temperature of 1000°C and exposure time of 2-5 hours, in a CO atmosphere, also produced the separation of the reduction products by melting. The distribution of iron and phosphorus was studied using an electron scanning microscope. The phase analysis of the samples was studied using a Rigaku Ultima IV X-ray diffractometer. The results were processed using the "Match" software. Reducing roasting in a CO atmosphere provides a transition from the oxide phase to the metallic phase of only iron and phosphorus without loss of manganese, thus increasing the concentration of MnO oxide in the residual oxide phase of the ore.

Abstract: It is usually necessary to first perform temperature reduction treatment to enable the catalyst to exert its catalytic activity in the subsequent process of preparing carbon nanotubes by chemical vapor deposition. In this experiment, Fe-Mo/Al₂O₃ catalyst was prepared based on microreactor, and the effect of reduction temperature on the microstructure of the catalyst and the morphology of carbon nanotubes was investigated. The results show that the reduction temperature has a significant effect on the microstructure of the catalyst, which in turn affects its catalytic activity and the yield and quality of carbon nanotubes. Moderately reducing the reduction temperature during the catalyst reduction process is beneficial to increase the catalytic activity of the catalyst. However, although its sintering degree could be weakened when the catalyst was reduced at an excessively low temperature of 350 °C, its catalytic efficiency was greatly reduced and the degree of defects of the catalyzed carbon nanotubes was increased. When the catalysts calcined at 450 °C and reduced at 600 °C, the catalysts show excellent catalytic activity, and catalytic efficiency can reach 74.76%. In addition, the reduction temperature also has a certain effect on carbon nanotubes. As the reduction temperature increases, the span of carbon nanotubes is relatively concentrated, but the specific gravity of the thicker outer diameter gradually increases. As for the defect degree of carbon nanotubes, the carbon nanotubes M_600-600 is better and the defects are fewer when the reduction temperature is reduced from 670 °C to 600 °C.

Abstract: Firing and metallization of brown iron ore from the Ayat deposit were investigated in present research. In order to remove carbon dioxide, carbonates, hydrated moisture and sulfur from the ore and convert goethite to hematite the oxidation firing was carried out in a Nabertherm muffle furnace at temperature of 900 ° C for 10 minutes. The effect of reduction of temperature was studied, by CO gas at 800, 900, 1000, 1050 ° C, for 3hours reduction time. The chemical composition of the initial and fired ore, as well as magnetic and non-magnetic parts of the reduced samples were studied by using an electron microscope. It was observed that at temperature of 800 ° C iron and phosphorus were not reduced. The metallized material with a low phosphorus content (0.1at%) was obtained at temperature of 1050 ° C.

Abstract: Ni₂P/TiO₂-Al₂O₃ catalysts were prepared by impregnation of nickel phosphate precursors followed by reduction in hydrogen. The catalysts were characterized by X-ray diffraction (XRD), N₂-adsorption specific surface area measurements (BET), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetry differential thermal analysis (TG-DTA). The effects of reduction temperature on catalyst structure and HDS activity were studied using a lab-scale continuous flow fixed-bed reactor.. The results indicated that the catalyst prepared with reduction temperature of 973 K exhibited the best performance. At a reaction temperature of 606 K, a pressure of 3.0 MPa, a hydrogen/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 2.0 h^-1, the conversion of DBT HDS was 96.0%.

Abstract: Pt catalysts have been researched and used for HI decomposition. Specifically, the effects of supports and reduction temperature on metal dispersion were investigated in this paper. Metal dispersion was high measured, in the order of Pt/Al₂O₃, Pt/ZrO₂, and Pt/SiO₂. HI conversion results coincided with the metal dispersion. With effect on reduction temperature, Pt dispersion was measured as 2.9 %, 26 %, and 60 % each 1173K, 973K, and 773 K. In addition, HI conversion presented 7.8%, 16.3%, and, 19.4% respectively. Consequently, Pt dispersion, influenced by supports and reduction temperature was considered to be crucial role in HI conversion.

Abstract: Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology of SSI and its removal ability for nitrate from wastewater, the influence of reduction temperature of SSI on nitrate removal was investigated. It was suggested that nitrate removal ability of SSI increased to the summit and then declined with the increasing of reduction temperature. When the reduction temperature of was T4, nitrate removal percentage reached to the maximum. When the original concentration of nitrate was only 5 mg-N/L, the additive quantity of SSI could prove plenty of zero-valent iron in a short time, and reduction temperature of SSI has little influence on nitrate removal. Nitrate removal by SSI appeared to be the pseudo-first-order reaction despite of reduction temperature. While nitrate original concentration was elevated to 50mg-N/L, the reaction order declined to the range of from 0.534 to 0.629 which was closed to 0.5, and the apparent reaction rate constant was 1.411 to 1.773 h-1.

Abstract: It is a good way that the fluidized bed is used as a substitute for reduction shaft in Corex process. Which can reduce energy consumption, environmental pollution and construction costs further, and also improve the competitiveness of Corex and blast furnace. At present, the sticking problem is present in iron ore reduction process and interrupts the reduction process, it has become a major obstacle on the development of fluidized bed. In this paper, a visualization hot model of fluidized bed is introduced. The influence factors on sticking behavior were analyzed from reduction temperature, gas velocity, atmosphere, degree of metallization or reduction and property of iron ore, the research provided a strong theoretical basis for controlling the sticking.

Abstract: Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To investigate the optimized method of nitrate removal from wastewater by SSI, dynamic testing of nitrate removal has been investigated. pH values should be elevated quickly after the addition of SSI, and nitrate removal percentage reached to more than 88% during dynamic state experiment. Nitrate removal expressed two-phase removal process including the nitrate removal percentage increasing phase persistently and the nitrate removal percentage maintaining constant phase. The reduction temperature of SSI has significant influence on nitrate removal during fore-period. When the nitrate concentration was 5mg-N/L, nitrate removal percentage could only amount to 60% even the libration time prolonged to 200h. When the nitrate concentration increased to 50mg-N/L, the nitrate removal concentration increased quickly to about 80% and then the removal percentage maintained about 88%.

Abstract: Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology, reductive kinetics of SSI was analyzed on the basement of unreacted core model. In the light of the single reaction surface theory, the ratio of internal diffusion resistance fI and chemical reaction resistance fR was calculated according to the weight loss curve of SSI reduction. Under different temperature, both fI and fR increased with the reaction time, especially the radium of unreacted core was small after a period of reaction time. Compared the ratio of fI and fR, it concluded that SSI reduced by hydrogen was controlled by the chemical reaction, combination of chemical reaction and the internal diffusion, the internal diffusion under the temperature being lower than T3, from T3 to T4, more than T5, respectively.

Abstract: Spherical sponge iron (SSI) with high activity and intension possesses potential characteristics to be utilized as wastewater treatment material. Influence of reductive temperature on specific surface area and distribution of holes with different diameter were investigated. It was suggested that reductive temperature has significant influence on the specific surface area of SSI. When the temperature was controlled at T1 to T5, the porosity was 42.57% to 51.91%. When the temperature was lower than T4, the specific surface area was belonged to the range from 1.867 m2/g and 3.089 m2/g, while which declined sharply to 0.616 m2/g as the temperature increased to T5. When the reductive temperature was lower than T4, mean pore size varied from 275.7 nm to 449.6 nm, while which increased abruptly to 1270 nm as temperature increased T5. To utilize the SSI in wastewater treatment to remove pollutants, T4 was the optimized temperature.