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Direct reduction processes can be divided roughly into two categories: gas-based and coal-based. In both cases, the objective of the process is to remove the oxygen contained in various forms of iron ore (sized ore, concentrates, pellets, mill scale, furnace dust, etc.) in order to convert the ore to metallic iron, without melting it (below 1,200 °C (2,190 °F)).
Plants for the production of pre-reduced iron ore are known as direct reduction plants. The principle involves exposing iron ore to the reducing action of a high-temperature gas (around 1000 °C). This gas is composed of carbon monoxide and dihydrogen, the proportions of which depend on the production process.
The HIsarna ironmaking process is a direct reduced iron process for iron making in which iron ore is processed almost directly into liquid iron ().The process combines two process units, the Cyclone Converter Furnace (CCF) for ore melting and pre-reduction and a Smelting Reduction Vessel (SRV) where the final reduction stage to liquid iron takes place.
Direct reduction methods such as this one offer the flexibility of using any solid fuel and in this case, 240 to 300 kg of hard coal is needed to process one metric ton of iron ore that contains 30 to 40% iron. Assuming a consumption of 300 kg/ton of ore at 30%, the hard coal consumption is 800 kg per ton of iron.
Direct-reduced iron can be produced from iron ore as it reacts with atomic hydrogen. Renewable hydrogen allows steelmaking without fossil fuels. Direct reduction occurs at 1,500 °F (820 °C). The iron is infused with carbon (from coal) in an electric arc furnace. Hydrogen electrolysis requires approximately 2600 kWh per ton of steel. Hydrogen ...
Iron ore pellets produced by LKAB, from ore mined in northern Sweden. Pellets are a processed form of iron ore utilized in the steel industry, specifically designed for direct application in blast furnaces or direct reduction plants. These pellets are spherical in shape, with diameters ranging from 8 to 18 millimeters.
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Direct reduction is the fraction of iron oxide reduction that occurs in a blast furnace due to the presence of coke carbon, while the remainder - indirect reduction - consists mainly of carbon monoxide from coke combustion. It should also be noted that many non-ferrous oxides are reduced by this type of reaction in a blast furnace.