The Mines and Geosciences Bureau (MGB) is now advancing studies on sponge iron as part of efforts to develop downstream industries for iron ores and take advantage of increasing demand both locally and abroad.
Citing the results of an initial study, the MGB-Metallurgical Technology Division said that utilization of local iron ore (fine magnetite) in the production of sponge iron showed promising results.
Sponge iron is an important input to the steel-making sector. It is produced from direct reduction of iron ore (in the form of lumps, pellets or fines) by a reducing gas produced from natural gas or coal.
“The undertaking could well lead to the creation and development of downstream industries for the local iron ores where demand for pre-reduced iron pellets or sponge iron is inevitably increasing,” the MGB said.
The initial phase of the research, conducted in the last quarter of 2013, has produced partially reduced iron where about 95 percent of the magnetite (Fe3O4) content of the samples was converted to hematite (Fe2O3).
“The initial phase of the study involved grinding, screening, magnetic separation, gravity concentration, pelletizing, reduction and chemical/XRF/XRD analyses. The results of mineral processing tests showed that magnetite ore (16-35 percent iron) can be upgraded to 58 percent iron magnetite concentrate using gravity and magnetic separation,” it said.
The MGB said that further tests are being conducted using electrically operated laboratory kiln to define the right combination of the operating parameters – including temperature, mass flow rate and charcoal addition.
For the next phase of the research, the MGB will subject the pre-reduced hematite pellets to a smelting process to produce sponge iron. This will be conducted in collaboration with the Metals Industry Research and Development Center (MIRDC) of the Department of Science and Technology.
Direct reduction, the process being adopted in the study, is the most developed technology in the production of sponge iron. It can be adopted locally because of the high melting point of the titanium dioxide (TiO2) content of Philippine fine magnetite ores where, during smelting, the ores produce a slag that detrimentally blocks conventional blast furnaces in the production of pig iron.