| BF gas dust and converter sludge，which contain many useful components, such as ironoxide and carbon, are metallurgical dust and slag that produced much in smelting process. Sothe recycle of BF gas dust and converter sludge will be of great importance in solving the steelenterprise resource shortage and reducing the cost of purchased ore. At present, the utilizationefficiency of metallurgical dust and slag is not high enough in domestic steel enterprise.generally it is used for returning sintering plants or to improving the grade of metallurgical dustand slag through mineral processing. But these methods can’t solve the problem for thecirculation enrichment of harmful elements in metallurgical dust and slag. On the reference tothe research findings of processing metallurgical dust and slag at home and abroad andcharacteristics of low grade and high carbon of metallurgical dust and slag, thecarbon-containing pellets dezincing reduction method is adopted to obtain metallizationpellets,which have good metallurgy performance.Firstly,the basic physicochemical of BF gas dust and Converter sludge were analyzed.Theresults showed carbon content was high in BF gas dust, and iron grade is lower than convertersludge. There was a small quantity of zinc in BF gas dust and converter sludge. The BF gas dustand Converter sludge’s bulk density is small，which is less than1.5g/cm3，the size distributionof that is more than0.15mm, and the particle size of BF gas dust was thinner than Convertersludge. Iron of BF gas dust was formed with high iron oxide, and the carbon particles were big.Iron formed Fe and FeO in Converter sludge, and was distributed evenly and particles wassmall, Harmful element zinc formed ZnFe2O4and existed in mixture phase of other oxides.Research on reduction kinetics of carbon-bearing pellets showed gasification diffusionwas the restriction step of reduction process in metallurgical dust and slag carbon-bearingpellets. The dynamic equation which took carbon gasification as the restriction step of earlyreduction of Carbon-bearing Pellets was ln[1-f(t)]=-19842.87e-151.306/RTt. The dynamic equationwhich took gasification diffusion as restriction step of later reduction of Carbon-bearingPellets was1-2f(t)/3-(1-f(t))2/3=1887.86e-151.938/RTt.Then, the experiment of briquetting of metallurgical dust and slag was studied, and theinfluence of types and dosage of binder, C/O, pressure, dosage of water have been analyzedsystemically, also the structure of microscopic of green pellets was studied by SEM and POM.The results showed the strength of pellets that used bentonite as binder was not well, andstrength of pellets that used Methylcellulose as binder met requirement. The best moldingparameters was methylcellulose dosage0.3%, water dosage10%and molding pressure75KN.The pore between the phases that inside the green pellets that respectively used bentonite andmethylcellulose as binder was larger and organization loosed, it is easy to cause the greenpellets low strength. But because Methylcellulose was strong bonding when it hydrolysis inwater, the strength of green pellets that used Methylcellulose as binder was higher.Finally, the effects of reduction temperature, reduction time and C/O on the reductioneffect of green pellets and phase structure of metallization pellets were studied by SEM. The results showed reduction temperature was significant influence on the metallization rate,dezincing degree and compressive strength of Metallization pellets. With the increasing ofreduction temperature, reduction time and the reducing of C/O, the Fe phase of metallizationpellets is increased and crystal connection is better, the metallization rate and compressivestrength of metallization pellets is higher. When C/O=1.0, at the reduction temperature above1220℃and reduction time above30min, the composition of iron is more than70%,themetallization rate was above88%, the zinc content was not more than0.05%, the dezincingdegree is more than90%and the compressive strength is more than300N. |
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