دانلود مقاله ترجمه شده اثر ته نشینی فاز پروسکایت بر ویسکوزیته فلز کوره حرارتی تیتانیوم – مجله الزویر

فهرست مطالب:

چکیده
۱ مقدمه
۲ آزمایش
۳ نتایج
۱ ۳ ویسکوزیته فلز تحت شرایط اکسیداسیون هم دما
۲ ۳ رسوب و رشد فاز پروسکایت تحت شرایط اکسیداسین ایزوترمال(هم دما)
۳ ۲ ۱ آنالیز فاز بلورین تحت شرایط اکسیداسیون هم دما
۳ ۲ ۲ رسوب فاز پروسکایت تحت شرایط اکسیداسیون هم دما
۳ ۲ ۳ رشد فاز پروسکایت تحت شرایط اکسیداسیون هم دما
۴ بحث
۵ نتیجه گیری

بخشی از ترجمه:

طی اکسیداسیون فلز مذاب، Ti+2 و Ti+3   به  Ti+4   اکسید شده و  تیتانگویت و دی.پسید غنی از تیتانیوم حاوی Ti+3  ناپدید می شود . در نتیجه  جزء تیتانیم  به طور انتخابی به فاز پروسکایت غنی سازی می شود. با افزایش زمان اکسیداسیون، مقدار تیتانیوم سریعا افزایش یافته و این که  زمان واکنش رسوب را افزایش می دهد:    که خود منجر به  تسریع غنی سازی تیتانیوم و رسوب فاز پروسکایت خواهد شد. در عین حال،  اکسیداسیون TiC  و آهن متالیک نه تنها منجر به کاهش ویسکوزیته می شود  بلکه منجر به افزایش سریع فلز فاز پروسکایت و تغییر فلز مذاب از حالت مذاب به ترکیبی از فاز مذاب و بلورین شده که به نوبه خود  افزایش ویسکوزیته فلز حرارتی اکسید شده را به مدت ۱۲ دقیقه  را در پی دارد.

بخشی از مقاله انگلیسی:

Introduction Every year more than three million tons of blast furnace slag containing 21–۲۴% TiO2 and 2–۴% metallic Fe are produced by smelting V–Ti-bearing magnetite in Panzhihua Iron and Steel Company. The Ti-bearing blast furnace slag is an important man-made resource. Due to the dispersed distribution of Ti component in various fine grained (<10 lm) mineral phases with the complex interfacial combination, it is difficult to recover the Ti component through traditional separation methods [1,2]. On the basis of the point of view of ongoing concern for both economic and resource, several mineral and metallurgy methods have been studied for treating the slag, such as flotation separation, combined with magnetic, hydrometallurgy and melting reduction [2]. However, the recovery and the utilization of each process were poor. So far the slag has not been efficiently utilized those results in a waste of the resource and the pollution of environment [2]. The main mineral phases in Ti-bearing blast furnace slag are titanium carbide, spinel, perovskite, titanaugite, Ti-rich diopside and metallic Fe [1]. The main titanium-containing mineral phases are perovskite, titanaugite and Ti-rich diopside. The perovskite is composed of Ti4+, and the titanaugite and Ti-rich diopside are composed of Ti2+ and Ti3+. Based on several studies and practices in a pilot plant on the slag [3–۱۱], blowing air to the molten slag, (Ti2+) and (Ti3+) in the slag were oxidized to (Ti4+), most of the Ti component in the slag was enriched into the perovskite phase which could fully grow and coarsen through the oxidation together with a heat treatment, and the perovskite phase could be separated from the slag by mineral dressing method. In order to obtain further information about the precipitation process of the perovskite phase, it is necessary to study the effects of the dynamic oxidation on the precipitation of the perovskite phase in the slag. The dynamic oxidation of the molten slag remarkably influences the viscosity and chemical composition, which play key role in the selective enrichment, precipitation and growth of the perovskite phase. Obtaining the slag with improved properties for utilization depend not only on the selective enrichment of the Ti component into the perovskite phase, but also on the precipitation, growth and coarsening of the perovskite phase developed through adjusting the viscosity and chemical composition under the dynamic oxidation condition. In other words, the dynamic oxidation of the molten slag is the crucial problem to the selective enrichment, precipitation and growth of the perovskite phase. The purpose of the present work is to study the effect of the perovskite phase on the viscosity of the slag under the dynamic oxidation condition through two aspects: the viscosity research, the precipitation and growth of the perovskite phase. 2. Experimental The slag in this study was from the Panzhihua Iron and Steel Company. Chemical composition of the slag is listed in Table 1. Before the experiment, the slag was milled to 120 lm and dried in an oven at 100 C for 3 h. The experiments were carried out in a horizontal MoSi2 furnace fitted with an type R thermocouple, which was controlled by the Shimaden SR – ۵۳ temperature programmed control instrument. The length of isothermal section was 60 mm, the temperature accuracy was within ±۳ C. The gas flow rate was controlled by a rotameter. The oxidation gas was compressed air. The slag samples were melted in a platinum crucible at 1420 C for 20 min, air was then blown into the molten slag at the flow rate of 1 L/min under isothermal condition for 2, 4, 6, 8, 10 and 12 min, respectively. The slag was then slowly cooled to room temperature at the cooling rate of 5 C/min. In this process, some samples were obtained by air quenching method at 1420 C for 2, 4, 6, 8, 10 and 12 min, respectively. The relationships between the viscosity and temperature of the raw slag and the oxidized slag were measured in ZCN-1600 high temperature viscometer. Because the (Ti2+) content in the slag is less, the (Ti2+) content is neglected. The FeO, Fe2O3 (FeO1.5), Ti2O3 and TiO2 content were measured by chemical titration analyses. The FeO content was determined by o-phenanthroline oxidation–reduction titration, and the Fe2O3 (FeO1.5) content determined indirectly by the TFe content and the FeO content. The Ti2O3 content was determined by reduction–oxidation titration, and the TiO2 content by ammonium ferric sulfate titration. Two repeated measurements were made for each experimental condition. The experimental error was between ±۰٫۰۶% and ±۰٫۱۳%. The experimental apparatus (ZCN-1600) for viscosity measurements consists of a high temperature furnace and viscometer. The raw and the oxidized slag were remelted in a vertical MoSi2 resistance furnace under purified argon atmosphere. A viscometer was conducted by loops to a platinum extension rod and to a measuring spindle made of molybdenum. The viscometer spindle was calibrated against standard oils (Brookfield). The spindle constant was determined by measuring the torque at several rotation speeds at immersion depths. After the molten state of the slag could be verified, the spindle rotating at a speed of 40–۶۰ rpm was lower into the slag. The viscosity of slag was then measured. The overall experimental errors of the viscosity measurement were estimated using the uncertainties associated with each experimental parameter. The uncertainties in the measurements on the liquid slag arises from the uncertainties of the calibrating oils (2%), viscometer accuracy (1%) and volume expansion of the measuring spindle (4%) and the immersion depth of the spindle (2%). The temperature uncertainty of the high temperature furnace is within ±۳ C. The overall uncertainties of the viscosity measurements are between ±۹% and ±۱۳%. After being polished, the microstructures of the oxidation products were characterized by Quantime520 image analysis, scanning electron microscopy (SEM) with energy dispersive spectrometory (EDS) and X-ray diffraction (XRD). The volume fraction and average grain size of perovskite phase were measured on a Quantime520 image analyzer by the line intercept method (average of 10 fields). The SEM machine is SSX-550, and the EDS machine is TN540. In addition, the XRD machine is D/MAX-RB, and the optical machine is PME OLYMPUS. The concentrations of crystalline phases can be determined by the volume fraction of the crystalline phases after the dynamic oxidation, but the volume fraction and grain size of crystalline phases (titanaugite and Ti-rich diopside) that are composed of TiO and Ti2O3 are very small after the dynamic oxidation, accordingly, it is very difficult to determine the concentrations of titanaugite and Ti-rich diopside by the volume fraction. On the other hand, the volume fraction and grain size of perovskite phase are very large after the dynamic oxidation, hence, the concentration of perovskite phase can be determined by the volume fraction. Analysis uncertainties of the volume fraction and average grain size measurements come from the sample homogeneity, magnification, and number of measured fields. The overall uncertainties of the volume fraction and average grain size measurements are between ±۷% and ±۱۵%.

دانلود رایگان مقاله انگلیسی

خرید ترجمه فارسی مقاله با فرمت ورد

خرید نسخه پاورپوینت این مقاله جهت ارائه