I want to know about the Iron Oxide and gas conversions for the different DRI Processes. Can I get the reference data for it?
dear Mr. Tahir
you need references or you need answers ... if you choose references I need to know, you need articles or books ... when you answer my questions, please talk more about your project ... best regards
raghd muhi al-deen jassim
Dear Sir Raghd Muhi Al-Deen Jassim,
I Want to know the values for the gas and Iron oxide Conversions for Direct reducd Iron process, Basically Its related to the reduction of Hematite into metallic Iron in the Shaft furnace. I want to know the Conversion of Gas ans Iron oxide, I want to know this Answer If there is availabe any paper or book its will be Good job.
Thanks a lot for your efforts.
Best Regards
MUHAMMAD TAHIR
DRI or sponge iron refers to porous iron produced by the DR process. The DR process is a solid-state reaction process (i.e., solid–solid or solid–gas reaction) in which removable oxygen is removed from the iron oxide, using coal or reformed natural gas as reductants, below the melting and fusion point of the lump ore or agglomerates of fine ore. The external shape of the ore remains unchanged.
DRI has been fast gaining ground throughout the world since the 1980s mainly because of the shortage of coking coal for BF and steel scrap in steelmaking. DRI is produced by the DR of iron ore by using noncoking coal/ natural gas. The major part of DRI production is used as a substitute for scrap in steelmaking. DRI is consumed in three primary product forms, namely, lump, pellets, and hot briquettes . The other secondary product form is cold briquettes made from DRI fines. The hot briquette form is popularly known as HBI. HBI is a combined solid form of DRI lump and pellets, hot pressed at 700–800C (973–1073 K), immediately after its production. The most important characteristics of HBI are its high density and lower specific area, which improves the resistance to reoxidation and makes it easier to handle. Due to high density, the charging of HBI in furnace is much easier and melting is faster.
Based on the types of reductant used, the DR processes can be broadly classified into two groups:
1. Using solid reductant, that is, coal-based DR process
2. Using gaseous reductant, that is, gas-based DR process
Coal-based processes
In coal-based DR processes, noncoking coal is used as reducing agent. In solid reduction processes, iron oxides together with solid reductant (noncoking coal) are charged into the reactor. The generation of reducing gas (mainly CO) takes place in the reduction reactor, and the product has to be separated from excess reductant, ash, and/or sulfur absorbing materials (lime, dolomite) by magnetic separation after discharge at low temperature, which makes product handling more complicated.[3] Because of the presence of these substances in DRI, hot briquetting and hot feeding are not possible for coal-based process. Magnetic separator also does not work at high temperatures to separate the DRI.
Gas-based processes
Reformed natural gas is used as a reducing agent. Iron ore lumps or pellets are reduced in the solid state and oxygen from iron oxide is removed by a gaseous reducing agent. Natural gas is reformed at 950C (1223 K), in the presence
of catalysts (Ni or Al2O3), to produce reducing gases CO and H2. The reducing gases H2, CO, or mixture of H2 and CO, are introduced into the reactor at elevated temperatures [up to 1000C (1273 K)] and pressure (up to 5 bars)[3]. If CH4 is present in the reducing gas, it results in carburization of the reduced product.
The processes based on gaseous reduction are confined to the areas where natural gas is available in abundance at a reasonable price.
The following are gas-based processes:
1. Retort processes HyL I, Hoganas
2. Shaft furnace processes Midrex, HyL III, Plasmared, Armco, Purofer, NSC, HyL IV
3. Fluidized bed processes FIOR, Finmet, Circored
DR processes are very sensitive to chemical and physical characteristics of raw materials used in the process. Iron ore or pellets, reductant (i.e., noncoking coal or natural gas), and limestone/dolomite are the main raw materials for DR technology. For successful operations the process of DR technology has specified the characteristics of raw materials to be used in the process.
Characteristics of iron ore: Lumps or pellets have high iron content, low gangue content, and good mechanical strength and are readily reducible and of nondecrepitating variety. Iron ore feed to the reactors has the following characteristics:
1. Chemical composition
2. Reduction properties
3. Physical characteristics
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