高碱度内配煤含铁团块自还原过程中脱硫和脱磷

Desulfurization and dephosphorization during self-reduction of high-basicity coal-bearing iron oxide briquettes

以转炉除尘灰、高炉瓦斯灰和硫酸渣为含铁原料,制成CaO/SiO2值为2.0、C/O摩尔比为1.1～1.2的高碱度内配煤含铁团块,在1330～1380℃下进行自还原,研究这一过程的脱硫和脱磷规律.结果表明:(1)高碱度内配煤含铁团块自还原过程中,通过还原气化脱硫可去除20%～40%的硫,其余的硫绝大部分存在于渣中,并通过渣铁分离被去除,总脱硫率高于97%.(2)过量的CaO可以抑制脉石中的P2O5被碳还原,已被还原的磷一部分被新生态的金属铁吸收,另一部分从团块内部逸出而去除.脉石中未被还原的P2O5最终可通过渣铁分离被去除,总脱磷率达到50%～60%.(3)高碱度内配煤含铁团块高温自还原法可制备出低硫、低磷的"纯净"金属铁粒.

High-basicity coal-bearing iron oxide briquettes with a CaO/SiO2 of 2.0 and a C/O molar ratio of 1.1 to 1.2,which were produced by BOF steelmaking sludge,BF dedusting ash and pyrite cinder,were self-reduced at temperatures from 1 330 ℃ to 1 380 ℃ to study the phenomena of desulfurization and dephosphorization.During the self-reduction,the desulfurization ratio by evaporating as COS is 20% to 40%.Residual sulphur is attached in slag and it can be separated from iron nuggets.The total desulfurization ratio is more than 97%.Excessive CaO in high-basicity coal-bearing iron oxide briquettes can restrain the reaction of phosphorous pentoxide reduced by carbon.The reduced phosphorous is partially absorbed by nascent metallic iron,and the other escapes from the briquettes.Phosphorous pentoxide attached in gangue which is not yet reduced can be separated from iron nuggets.The total dephosphorization ratio can reach up to 50% to 60%.It is indicated that clean iron nuggets with low sulphur and low phosphorous can be produced by self-reduction of high-basicity coal-bearing iron oxide briquettes