6555

6120

كارشناسي ارشد

استخراج فلزات

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1390

پانزده، 105ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

محمد حسن عباسي، مسعود پنجه پور

15/1/90

علي شفيعي، محمد حسين عنايتي

1396/10/10

كتابنامه

مواد

مهندسي مواد

ID6120

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Investigation of Mechanical Activation on Hematite Graphite Reduction Kinetics in the Presence of Iron Fatemeh Mohseni Email address f mohsenihabibabadi@ma iut ac ir Date of Submission 2011 08 13 Department of Materials Engineering IsfahanUniversity of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor s Name Mohammad Hasan Abbasi Professor Abbasi32@cc iut ac ir Masoud Panjepour Assistant Professor Panjepour@cc iut ac ir Abstract In this study the effect of mechanical activation on structural changes reducing behavior and reduction kinetics of the hematite Graphite mixture in the presence of Iron was investigated For this purpose a mixture of hematite graphite with the stoichiometric ratio C O 1 in the presence of different amounts of iron 0 5 and 10 wt was milled from 0 to 50 hours In order to study structural changes in the process of grinding XRD analysis was performed on the samples The morphology of the powder mixture during milling was studied using SEM analysis It is obsereved that after 5h millig the peak corresponding to graphite was completely eliminated that was concerned to amorphisation of graphite structure It was founded that with increasing milling time the diffraction patterns of the magnetite peak gradually appeared and their intensity increased Also the wustite peak appeared in diffraction pattern whith 50h milling It was concern to reduction of some hematite to magnetite and wustite during milling The grain size and lattice strain of hematite powder particles were determined using the Williamson Hall method Also mechanical activation parameter d was calculated and used as a criterion of the energy stored in the powder mixture The results showed that the existing of Iron had positive effect on decreesing of grain size increasing structural strain and mechanical activation parameter SEM images showed the formation of dense structures in the long time of milling indicating the amount of energy stored in the powder particles Reducing and kinetic behavior of the samples was studied using TG DTA analysis by 10 15 and 20 C min of heating rate from room temperature to 1200 C The results showed that with increasing milling time temperature of reaction initiation reduced Reduction patterns showed that the start temperature of the reduction in presence of 5 wt of iron was reduced 60 C Reduction kinetics studies was carried out using model free method of Ozawa FWO and Kissinger KAS and the constant slope fitting method These studies showed that the grinding reduces the activation energy of reduction For example 50 hours of milling reduces the activation energy to 50 percent The presence of iron was very effective so that in the presence of 5 wt iron the activation energy decreased to less than one third Calculation of activation energy of the activated and inactivated samples by model free and constant slope methods and their comparison showed that the reaction was of chemical control type and the carbon gasification reaction was determined as the controlling step in presence and absence of Iron for the carbothermic reduction of hematite with graphite Keywords Carbothermic reduction kinetic analysis thermal analysis mechanical activation catalyst activation energy catalytic effect of iron hematit

محمد حسن عباسي، مسعود پنجه پور

علي شفيعي، محمد حسين عنايتي