Reduction Model For Gas Magnetization Roasting Of Single Limonite Particle

Iron ore is the main raw materials of iron and steel metallurgical industry, and is theimportant mineral resources for the sustainable development of national economy. The ironore containing with reserving up to10billion tons of limonite, hematite, siderite which isdifficult to be chosen, if we can take effective magnetization roasting magnetic separationtechnology processing, iron ore can be converted into real strategic reserves, so thedevelopment of new iron ore resources has become the top priority. However, theconventional magnetization roasting technology process is complex, the disadvantages ofhigh cost, which is difficult to achieve large-scale industrial application. Aiming at thisproblem, in this paper, a gas solid fluidized advantage of high efficiency heat transfer andmass transfer of baiyun obo magnetizing reduction roasting limonite particles is used in thenumerical simulation research. Limonite particles contain water of crystallization, and thecharacteristics of its’ poor, thin, miscellaneous, lead to problems in terms of physicalseparation. By developing of low grade ore magnetization roasting technology, we canefficiently use of waste resources and cost savings. Fluidized bed magnetization roasting ofcarbon monoxide developed rapidly in recent years, but single particle reduction processhas not been reported. The reduction model of single limonite particle is applied to explorethe reduction degree in the process of gas magnetization roasting.The magnetizing reduction roasting of the limonite particles in the CirculatingFluidized Bed always with heat transfer mass transfer chemical reactions and changes inpore structure of limonite particles, so the reduction characteristic of the limonite particle isvery complicated, to describe the reduction characteristic of limonite particles, we need toset up a mutually model which can transfer heat and mass, and with the changeable porestructure. This paper considered the complexity of the process for the limonite particles reduction, described the process of limonite particles internal gas diffusion reduction pore structure s change, morphological changes, heat transfer and mass transfer. Throughthe research of the process, in the diffusion-kinetics controlling region, we can build a reduction model of the particle particles. Due to the complex physical and chemicalprocess in the process of the limonite particles reduction, and the existence of the pore inlimonite particles, the chemical reactions happens at both interior and exterior surface oflimonite particles, these physical and chemical processes also have a great influence on thebuilding of the model. So, this paper discussed around this complex process and mainlyinvolves the following matters:This paper studied how the structure of limonite particles influence the process ofreduction, proposed an improved random pore model in gas-solid reaction, described thepore structure change of limonite particles, and verified the accuracy of the model byexperiment. It studied the distribution of carbon monoxide molecules along the radialdirection within limonite particle, the diffusion mainly including Knudsen diffusion andBulk diffusion, built the mass transfer equation. Then simulated the reaction process ofsingle limonite particle of Fe2O3into Fe3O4, then predicted the change of the relationshipbetween reduction time and reduction degree ender the different external conditions oftemperature and gas concentration. Considered the existence of the gas-solid reactionresistance, and then established a new model of magnetizing reduction roasting in full scale.Studied on the characteristics of full scale reduction of the new model reduction withconsidering the important parameters of reduction on single limonite particle ofenvironment temperature and initial concentration, and we obtained the change of eachpoint reduction distribution and overall reduction degrees with the change of timerespectively. Finally, by using FVM, discrete control equations, boundary conditions,FORTRAN programming, TDMA, this paper simulated the magnetizing reduction roastingcharacteristics of the limonite particles.To sum up, in this paper, in order to develop a new type of magnetization roastingtechnology, reduce the cost of roasting, through the research and analysis on themechanism of limonite reduction process, this paper provides effective information andsignificant instruction.