Decomposition Of Siderite And Iron Ore Powder's Reduction Characteristics In Suspended State Research

For the traditional blast furnace ironmaking exist large investment, high energyconsumption, long process and other shortcomings, our team proposes a short processand energy-saving new technology of ironmaking, in which the iron powder isreduceded directly by using non-coking coal. The following basic research work wascarried out for the process that siderite powder is preheated and reduceded firstly in thepaper. Using the two kinds of the siderite and iron oxide powder as the raw materials tostudy the effects of carbon dioxide concentrations and particle size on the kinetics ofsiderite thermal decomposition, reduction characteristic of iron ore powder in simulatedsuspention. The results showed that:1. Siderite thermal decomposition process coud be both modelled as a randomlynucleation under different CO2concentrations, accompanied by its growth. The reactionorder of siderite thermal decomposition varied from1to4. The higher the CO2concentration was, the higher activation energy E and pre-exponential factor lnA couldbe. It was measured and calculated that the activation energy varied from220.15to1365.20kJ/mol and the pre-exponential factor lnA changed from11.25to169.71. Inaddition, the activation energy E rised exponentially with an increase of CO2concentration, fllowed a relationship asE55.167Cco0.694602.2. Siderite particle size is an important factor affecting its pyrolysis kinetics, whenits size is less than1.6mm, it will have little impact on the activation energy ofpyrolysis. particle size distribution of siderite in30~224um range, the heat transferand mass transfer process of siderite pyrolysis will be weaken or simplified, so thereaction-order model F1with reaction rate controlling mechanism is the best model fitting the experiment date of it, while particle size distribution of siderite in400~500umum and900~1600um range, The shrinking sphere model and shrinking cylinder modelwith phase boundary reaction rate mechanism are respectively best for them.3. When the iron oxide and siderite micropowder in simulating fluidization statewere reducded isothermally under the conditions of different concentration of CO,within the range of850~1050?. Reduction rate reached the maximum in the initialphase, declined rapidly, and then flattened out. The influence of temperature on thereduction degree is less than the effect of reducing gas concentration.4. Within850~1050?, CO reduction reaction of iron oxide powder in suspendedstate experienced three stages, the first stage of the reduction progress agreed withRandom successive nucleation growth model?the second stage agreed with theChemieal reaction model?the third stage agreed with the three Dimensional diffusionmodel.