Kinetics Study On Solid-state Decarbonization Of High-carbon Ferromanganese Powder By Microwave Heating

Iron and steel industry consumed the world's 90% ferromanganese. Ferromanganeses are used in the production of almost all kinds of steel.Owing to sustainable growth of steel both in domestic and international market,the demand for ferromanganese increased significantly.Compared with rapid growth of high-carbon ferromanganese,the annual demand growth of low-carbon ferromanganese have shown a multiple.Low-carbon ferromanganese production by traditional methods were in liquid and cannot avoid problem of serious volatile of manganese,so people paid more attention to solid-state decarbonization of high-carbon ferromanganese to produce low-carbon ferromanganese.Microwave is a rapid,efficient and clean energy in metallurgical powder heating.As a kind of new heating technology,microwave is different from the conventional heating methods.Object is heated from outside to inside through the conduction,convection and radiation by external heat source in conventional heating,microwave heating is "body heating" caused by electromagnetic properties changing of material in the electromagnetic field.Microwave heating possess features of selective,timeliness,integrity, efficiency and cleanliness.A large number of experiments and studies have proof that microwave heating can remarkably promote reactions.High-carbon ferromanganese powder solid-state decarbonization were studied both in microwave heating spout-fluidized bed and microwave heating fixed bed,attempts to study whether microwave heating field have the ability to enhanced diffusion of carbon ions of high-carbon ferromanganese.Using air as fluidizing gas,the cold-state fluidized simulation and gas-solid fluidized decarbonization in microwave heating of high-carbon ferromanganese were carried out.Cold-state experiment showed that,spout-fluidized bed is more suitable for the fluidization of high-carbon ferromanganese powder than fluidized bed;in the experimental spout-fluidized bed,material weight of 500 g corresponding to the gas flow of 0.4 m3·h-1,material weight of 750 g corresponding to the gas flow of 0.8m3·h-1.Material weight is 750 g and air flow is 1.0 m3·h-1 in fluidization decarbonization experiment.The carbon content of high-carbon ferromanganese reducing 1.0% with heating temperature 500-600℃and holding time 60 min,reducing 1.4% with heating temperature 700-800℃and holding time 60 min;effect of holding time on decarbonization can be ignored,but the effect of decarbonization temperature is appreciable. The decarbonizer of solid-solid state decarbonization experiment of high-carbon ferromanganese powder is calcium carbonate powder.In the decarbonization conditions of C:CO2 is 1:1,the microwave heating temperature are 900℃,1000℃,1100℃,1200℃and the holding time are 0 min,20 min,40 min,60 min.Experiment results showed that,with the increase of holding time and hoeating temperature,the results of decarbonization become better and better.In condition of C:CO2 is 1:1.8,the uniform mixture was heated to 900℃,1000℃,1100℃,1200℃in microwave oven and muffle furnace,holding time is 60 min.Experiment results showed that,microwave heating is more efficiency than conventional heating;in the same conditions of material quality ratio,holding time and heating temperature,the decarbonization rate is higher and metal loss rate is lower in microwave oven.