The Research Of The Direct Reduction Of Iron And Roasting Based On Lignite Solid Char

In this paper, the direct reduction of iron ore (DRI) and roasting-magnetic separation experiments with the lignite solid char in vertical furnace are investigated. Based on Huolinhe lignite and semi-coke from low temperature pyrolysis as reducing agent, direct reduction with high-grade iron ore and roasting magnetic separation with low-grade iron ore are studied. The analysis of Huolinhe lignite shows that:the lignite with low fixed carbon and high volatile content is not suitable to be used as metallurgical reductant directly; gasification reactivity of the lignite has reached98.5%at900℃, indicating that Huolinhe lignite has favorable gasification reactivity, if modified to improve the content of fixed carbon and lower volatile content, Huolinhe lignite may be an excellent metallurgical reductant.Detailed studies based on the mineralogy of two iron ores show that:Gongchangling hematite is a high-grade iron ore with iron grade60.88%and low S, P contents, quartz is the main gangue mineral, thus Gongchangling hematite is a fine raw material suitable for direct reduction; Corresponding, Jiaozuo hematite is a low-grade iron ore with iron grade29.52%, as a common low-grade iron ore with low S、P contents, acidic gangue is the main gangue, fine-grained hematite distributes in the gangue, enrichment of Jiaozuo iron ore as the ore is used as iron-making raw materials.Pyrolysis experiments of Huolinhe lignite show that:the highest yield of tar under the optimum pyrolysis conditions is at560℃, thus direct reduction and roasting magnetic separation use500℃pyrolysis char as reductant.The direct reduction experiments of Gongchangling iron ore show that, the optimum experimental conditions are as follows:reduction temperature is950℃, reaction time is1.5h, char consumption ratio is0.4, under these conditions, a direct reduction grade85.04%Fe with metallization93.11%can be obtained, after magnetic separation of DRI, high-quality iron with93.15%Fe and metallization90.36%can be obtained which can meet the requirements of the EAF steelmaking. The roasting-magnetic separation experiments of Jiaozuo iron ore show that, the optimum experimental conductions are as follows:roast temperature650℃, roast time20min, char consumption ratio is0.4, under these conditions, the indexes of iron concentrate high-intensity are iron grade47.78%and iron recovery rate97.78%through magnetic separation which can meet the requirements of low-grade iron ore enrichment.