SPONGE IRON

Iron ore (haematite) and non-coking coal are the prime raw materials for the production of sponge iron. These are charged into a rotary kiln in requisite proportion along with some dolomite. Coal plays a dual role in the process by acting as a reductant as well as a fuel for providing heat to maintain the requisite temperature inside the kiln at 950-1050C. The reduction process occurs in solid state. The crucial factor in this reduction process is the controlled combustion of coal and its conversion to carbon monoxide to remove oxygen from the iron ore.

The overall process requires duration of approximately ten to twelve hours inside the kiln, during which iron ore is optimally reduced and discharged to a rotary cooler for cooling below 120°C., before coming out into the finished product circuit.

The process of sponge iron making aims to remove oxygen from iron ore. When that occurs, the departing oxygen causes micro pores in the ore body making it porous. The final product, when observed under a microscope, resembles a honeycomb structure looking spongy in texture, hence the name sponge iron.

Sponge iron is distinct due to its high metallic iron content and consistent chemical and physical characteristics. This provides secondary steel makers flexibility in preparing their furnace charge to produce finer quality steels than what is possible using steel scrap only. Some of the features of the sponge iron produced are:


+ High iron content and high degree of metallization

+ Uniform and consistent quality

+ Lower sulphur and phosphorus content

+ Negligible tramp element

+ Minimum dust generation during material handling

+ Good flow ability in bins, pipes and conveyors for continuous and trouble free charging

+ Superior technical support to induction furnace operators

+ The quality of sponge iron is primarily ascertained by the percentage of metallization (removal of oxygen), which is the ratio of metallic iron to      the total iron present in the product.

The properties of sponge iron typically produced are: