Sponge iron is a spongy mass that contain a mixture of slag and wrought iron.
Sponge iron is manufactured by reducing iron ore to metallic iron with the help of coke or charcoal at temperatures lower than the melting point of iron. Latest methods produce sponge without melting the iron ore.

Use of sponge iron
Through not useful itself, sponge iron is processed to manufacture wrought iron. Spongy iron is beaten with hammers to remove the slag. It is also oxidized to remove carbon or carbide. After the treatment, wrought iron is produced, which consists of some percentage of slag and other impurities. Further treatment may include stages of steeling.

There are several procedures to manufacture sponge iron. Sponge iron have very low levels of contaminants, sulfur and phosphorus, which make it suitable as scrap substitute in steelmaking process. If produced onsite, sponge iron is best suitable raw materials for steelmaking.

Features and Specifications
Specifications

Characterisitic	Requirement
% Non-magnetic	1.0 Max.
% Metalic Fe	81 Min.
% Total Fe	91 Min.
Metallisation	88 Min.
%Phosphorous	0.05 Max.
% Sulphur	0.03%
% Carbon	0.3 Max.
% SiO2+ Al2O3	5 Max.

Size: A grade Lumps 3-20 mm (-3 mm 5% Max.)
A grade Fines 0-6 mm (+6 mm 5% Max.)

The main raw materials for stainless steel is recycled scrap but some virgin material is added in the form of alloying agents (e.g. ferrochrome, ferronickel etc.).Although these alloying agents are recycled as part of the stainless steel cycle, there is not enough scrap containing nickel and chromium on the market to satisfy the demand for production of new stainless steel. Virgin ore is thus invested in the future steel cycle.