Effect of Briquette Thickness on Iron Nugget Formation in Fluxless Processing of Iron Sand Concentrate under Isothermal – Temperature Gradient Profiles

Abstract

Currently, electric furnaces and blast furnaces are used to process iron sand concentrate or titanomagnetite to produce pig iron and titanium slag. The titania content in the slag ranges from 10 to 25 mass% of blast furnaces and 30 to 35 mass% of electric furnaces. The low titania content in the slag is due to the addition of flux, some iron oxide must be retained in the slag to adjust the viscosity of the slag and the mixing of iron sand concentrate with ordinary iron ore. The low titania content in the slag makes titania extraction economically unattractive. One method to achieve high titania slag is the carbothermic reduction process without flux addition. A series of experiments have been carried out on the carbothermic reduction of cylindrical briquettes consisting of iron sand concentrate and coal under an isothermal – temperature gradient profile up to 1380°C to produce iron nuggets separated from slag. The briquettes have a diameter of 13 mm, and the thickness varied from 2 to 18 mm. The results showed that the thickness of the briquettes significantly affected the iron recovery in the nuggets. The briquettes with 2 mm thickness showed higher iron recovery in the nugget. The study also found that the sulfur content in coal may have contributed to the formation of iron nuggets.