An investigation into causes of degradation of carbon-containing pellet in production of zinc-containing dust sludge treated in rotary hearth furnace
The rotary hearth furnace(RHF)process is one of the effective ways to dispose of zinc-containing dust in the iron and steel industry in China.Currently,there is serious degradation of carbon-containing pellets in the process of treating zinc-containing dust and sludge by the RHF process,which adversely affects the smooth operation of the production line and product quality.Therefore,the degradation phenomenon of carbon-containing pellets in each process of RHF was systematically analyzed,such as raw material pretreatment system,balling system,drying system,direct reduction system of RHF,and pellets cooling system.The analysis results show that the degradation of carbon-containing pellets mainly includes natural degradation and reduced degradation.The main reason for natural degradation is the incomplete digestion of active calcium oxide(f-CaO)in the steelmaking dust sludge and the difference in surface vaporization and internal diffusion speed of moisture in carbon-containing pellet during the drying process.The main reason for reduction degradation is the crystalline transformation and crystal volume change of the iron-containing phase during the reduction process at low temperature(400-600 ℃).
rotary hearth furnacezinc-containing dust sludgedegradationresource recyclingmetallurgical dust and sludge
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