Manufacturer of SPONGE IRON

Selection of a suitable production process and the capacity of the production units from the nucleus around which the basic concept of a plant is developed. While the selection of a process takes into account factors like, type of products, availability and amenability of local raw material, process status, specific energy consumption, level of energy required, environmental pollution etc. The capacity selection of major units would depend on the volume of production, available unit sizes, economies of scale etc. The basic process of manufacture of sponge iron is very simple. The percentage of oxygen associated with iron as oxide is removed from the ore particles and the process is often referred to as "Percentage Reduction"; whereas the percentage of iron forming a part of the whole iron, and which exists in the metallic form, is clued the degree of metallisation in sponge iron making technology. Direct reduction processes can be broadly classified into to groups based on the type of the reluctant used namely solid or gaseous. There are two well-established processes for the manufacture of sponge iron, namely

        The reformed natural gas process i.e. by the gaseous reduction of the iron ore.
        Coal based Rotary Kiln process - Solid Reduction.


India there is no plant using liquid fuel for the reduction of iron ore since it's availability is problematic and injection of iron ore's done in the form of pellets, which becomes very expensive. All the gas based plants in operation use natural gas as the reluctant and are all along the HBJ line. The natural gas is under the GAIL control, which is a government organisation, and the steel sector is not the priority sector for the sanctioning of the gas.

Most of the solid reluctant based processes use non-cooking coal as reluctant. As the non-cooking coals are available abundantly in our country the processes utilising the non-cooking as reluctant are of much significance to us. The different important types of coal based processes are as follows :


        HYCL Process, This is highly flexible.
        MIDREX Process, continuous; similar to blast furnace,
        FLUIDISED BED Process
        SL/RN Process, useful when coal of low ash & sulphur content available
        ROTARY KILN Process, the most widely accepted process.


The ITC Technology which has experience in operation of smaller plants using the wide range of raw materials from different sources like iron ores from Ballery-Hospet region, Bailadilla, Barbil etc. The different size ranges of the iron ores like 3-6 MM, 3-12 MM, 5-15 MM, 5-20 MM etc. in combination with various size ranges of feed coal like 3-6 MM, 5-12 MM, 5-18 MM etc. have been tried. The size combination of various types of coals with different iron ores has also been tried and the parameters were optimised.


PROCESS DESCRIPTION

Sponge Iron production using coal involves reducing iron ore with Solid Carbonaceous material such as coal, coke or lignite. The reduction is carried out in a Rotary Kiln at a pre-determined temperature and controlled atmosphere and then cooled to ambient in the Rotary Cooler with Indirect Water Cooling System. The input raw materials i.e. iron ore, coal and limestone in the required calibrated size are fed into the rotary kiln, through fed tube in a pre-determined ratio by electronic weighing equipment, which is inclined and rotates at a required range of speeds. The kiln has five shell air fans mounted on the top which blow air in the respective zones to maintain the required temperature profile. The material and the hot gases move in the counter current direction as a result the iron ore gets pre-heated and gradually reduced by the time it reaches the discharged ends. Due the inclination and the rotary motion of the kiln, the raw materials move from the feed end to the discharge end. In the process it gets pre-heated at temperature range of 200-800 oC and reduced to sponge iron. The materials discharged from the kiln is taken into a rotary cooler via transfer chute where the material is cooled. The cooled product at about a temperature of 80oC. is discharged from the cooler and taken to the product separation and handling system through the cooler discharge conveyor. A diversion chute is provided at the heat end of this conveyor for diversion of the material in case of break down in the product separation. In product separation system consisting of double deck screen, the material is screened to 0.3 mm and 3-20 mm size fractions. The product, which consists of sponge iron and non-magnetic such as char etc. is screened to different size fractions and then magnetically separated by means of magnetic separators. Sponge iron is taken to a storage bin for dispatch. The char, which is not magnetic and contains a certain amount of carbons, is taken into a separate bin and can be recycled if found suitable or alternatively sold as fuel for applications such as in brick making and so on.