The Role of a Mixture of Coal and Dolomite in the Direct Reduction Process of Low-Grade Iron Sand Concentrate: A Pilot-Scale Study

The direct reduction process is one of the solutions for the manufacturing of iron which is energy-efficient and low in CO₂ emissions. Titanomagnetite-type iron sand is an important alternative source of iron minerals for countries with long coastlines. Thus, the process of making iron through direct reduction and using iron sand as the main raw material becomes an environmentally friendly solution, especially for countries that do not have primary iron ore reserves. This study aimed to analyze the process of direct reduction in low-grade iron sand by using the ratio variation between coal and dolomite used in bed mixture. In addition, this research was also conducted on a pilot-scale and used a gas-fired furnace to simulate the real conditions in industrial practices. The research began with the characterization of the materials used (iron sand concentrate, coal, and dolomite). Furthermore, the direct reduction process was carried out at 1300 °C with a total preheating-firing-cooling time of 24 h. Then, the direct reduction product was tested using X-ray fluorescence, scanning electron microscope, degree of metallization, and X-ray diffractometer. This research succeeded in providing an initial overview of real processes on an industrial scale. The direct reduction product had the highest total iron content of 64.8% or an increase of about 13.57% from the initial iron content in the concentrate. In addition, an iron phase was formed in the product which indicates that the direct reduction process had been successful.