Hematite (CAS 1317-60-8) is the world's most important iron ore, but processing it can be challenging, especially when dealing with fine-grained or complex ore bodies. Magnetic roasting is a crucial thermal treatment process that significantly enhances the efficiency of iron recovery from such difficult-to-process hematite ores. At Ningbo Inno Pharmchem Co., Ltd., we understand the value of advanced metallurgical techniques like magnetic roasting in maximizing resource utilization.

The principle behind magnetic roasting is to convert less magnetic or non-magnetic iron-bearing minerals into strongly magnetic ones, primarily magnetite (Fe3O4). Hematite itself is only weakly magnetic. However, when subjected to high temperatures (typically 700-900°C) in a controlled reducing atmosphere, hematite can be reduced to magnetite. This transformation is critical because magnetite is highly responsive to magnetic separation, a process that is generally more cost-effective and environmentally benign than many other separation techniques.

The magnetic roasting process typically involves several stages. First, the hematite ore is finely ground to liberate the mineral particles. Then, it is fed into a roasting furnace. Inside the furnace, a reducing agent, often carbon monoxide or hydrogen generated from fuels like natural gas or pulverized coal, reacts with the hematite, removing oxygen atoms and forming magnetite. The specific temperature, atmosphere, and residence time within the roaster are carefully controlled to ensure the efficient conversion of hematite to magnetite without over-reduction, which could lead to iron loss or the formation of unwanted phases.

Following the magnetic roasting, the treated ore is then subjected to magnetic separation. The now strongly magnetic magnetite particles are easily attracted by powerful magnetic fields, allowing them to be efficiently separated from the non-magnetic gangue materials. This step significantly increases the iron content in the concentrate. The resulting high-grade magnetite concentrate can then be further processed, often by pelletizing, before being sent to blast furnaces for iron production.

While magnetic roasting requires substantial energy input and specialized equipment, its benefits in processing low-grade or fine-grained hematite ores can be substantial. It allows for the economic recovery of iron from deposits that might otherwise be uneconomical to exploit. This technique is particularly valuable in extending the life of existing mines and unlocking new reserves of iron ore. Ningbo Inno Pharmchem Co., Ltd. recognizes the strategic importance of such advanced metallurgical processes in ensuring a stable and efficient supply of iron ore products for global industries.