Research work has been carried out on thereduction of FeO from liquid slags of the CaO-FeO-SiO_2ternary system using a graphite rotating disc technique. Theinvestigations were conducted on slags with a basicity ofCaO/SiO_2 = 1.27 and FeO contents of 20 and 60 percent, attemperatures of 1350 and 1420 deg C. The calculated viscosityrange for these slags is within 2.53-0.43 dPa.s. It has beenfound that the factor controlling the reduction process isdiffusion of FeO towards the disc surface, both in the case ofthe reduction from the slag with 20 percent FeO and in the caseof the reduction from the slag with 60 percent FeO fraction.The diffusion coefficient of FeO at the reduction temperatureof 1350 deg C is of the order of magnitudes of 10~(-7) cm~2/s,while at 1420 deg C it reaches the order of 10~(-6) cm~2/s.The calculated thickness values for the limiting diffusion layersrange from 8.54?10~(-3) to 0.70?10~(-3) cm. It has been foundthat with increasing reduction rate also Boudouard's reactionstarts to be important to the overall reduction rate. The limitingreduction rate at which Boudouard's reaction starts to beimportant to the entire process is dependent on temperature,being approximately 10.0?10~(-6) mol FeO/cm~2 s at 1350 degC, and approximately 15.0?10~(-6) mol FeO/cm~2 s at 1420 deg C.
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