Pelletizing & Steel Making


Iron Ore Pellets are formed from iron concentrate or run of mine iron fines. the plants consist of many pieces of equipment. The major areas or processes in the plant are mixing, balling, indurating and product handling.

Mixing is where the properly ground ore is combined with binding agents like Bentonite or organic binders, fluxing agents like limestone or dolomite, and if the ore is a Hematite with coke or anthracite coal as an internal fuel. The mixing is done usually in vertical or horizontal high intensity mixers to achieve a homogenous blend of ore and additives.

From mixing the filter cake is sent to the balling area where the ore is agglomerated on balling discs or balling drums into green (or unfired) pellets. Both drums and discs ball the ore to about 9-16mm size. Drums typically have very high recycle rates so have a screening circuit to screen out undersize and oversize pieces to be put back through the drum. Discs usually do not have a separate screening circuit at the disc.

Green pellets are then transported to the induration process. Pellets that are oversized or undersized and any fines generated during the balling or transporting process are screened right before entering the induration machine and sent back to the mixer or the balling area. The on-size pellets are then fed to the induration machine. The induration machine are usually two types, the strait grates and grate kilns. Both kilns dry the pellets out in a drying section, then bring the pellets up to a temperature of about 800-900 °C in a preheat zone, then finish the induration process at roughly 1200-1350 °C. The pellets are then cooled to a suitable temperature for transporting to a load out facility. Both processes recycle the heat from the pellet back through the process to aid in energy efficiency and decrease fuel usage

Steel Making

Iron ore is usually a mixture of iron and vast quantities of impurities such as sand and clay referred to as gangue. The iron found in iron ores are found in the form of iron oxides. As a result of these impurities, iron must be first separated from the gangue and then converted to pure iron. This is accomplished by the method of pyrometallurgy. The production of iron from its ore involves an oxidation-reduction reaction Currently majority of the world’s steel is produced through either one of the two main routes; the integrated Blast Furnace-Basic Oxygen Furnace (BF – BOF) route or the Direct Reduced Iron - Electric Arc Furnace (DRI - EAF) route.

Blast furnace, a vertical shaft furnace that produces liquid metals by the reaction of a flow of air introduced under pressure into the bottom of the furnace with a mixture of metallic ore, coke, and flux fed into the top. Blast furnaces are used to produce pig iron from iron ore. The product of blast furnace converted to steel in Basic Oxygen furnace.

Blast furnace hot metal production is still the prevalent process but it has declined over the years due to diminishing quality of metallurgical coke, low supply of scrap metal and environmental problems associated with the process. These factors have contributed to the development of alternative technologies of ironmaking, of which Direct Reduction (DR).

Direct reduction processes reduce iron ore (in the form of lumps, pellets or fines) to the solid state using a reducing gas to produce Direct Reduced Iron (also known as sponge iron). Depending on the source of reducing gas, DR processes can be described either as gas-based or coal-based.

Direct-reduced iron is obtained when fine ore and lump ore are reduced in a solid state at the relatively low temperature of about 1,000 ˚ c using reformed natural gas or elemental carbon produced from natural gas or coal. The Midrex and HYL processes are now most commonly used for direct reduction. Direct reduced iron (DRI), also called sponge iron.

Sponge iron and pig iron are semi-finished products and should be melted and purified. then excessive carbon is removed by the Basic Oxygen Furnace (BOF) or electric arc furnace (EAF), And then product can be either slabs, blooms or billets. The Basic oxygen furnace is used for pig iron, while the Electric Arc Furnace (EAF) is mainly used for sponge iron.

An electric arc furnace (EAF) is a furnace that heats material by means of an electric arc, combined with the action of chemical power provided by the use of oxygen and fuel to make steel. A basic oxygen furnace is a reactor in which oxygen is blown through molten pig iron that is heated to approximately 1,600℃ to convert it into steel.

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