Direct Reduced Iron: Difference between revisions
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==Product ecology== | ==Product ecology== | ||
'''[[Induction_Furnace]]''' -- could be fed with HDRI | '''[[Induction_Furnace]]''' -- could be fed with HDRI for energy-efficient steel production | ||
'''[[Gasifier]]''' -- to create the reducing gas: [http://www.openfarmtech.org/index.php/Compressed_Fuel_Gas syngas] is a mixture of H and CO | '''[[Gasifier]]''' -- to create the reducing gas: [http://www.openfarmtech.org/index.php/Compressed_Fuel_Gas syngas] is a mixture of H and CO | ||
'''Biogas''' -- methane from biogas can be turned into the H/CO mix. Globally, fossil gas (a.k.a. "natural" gas) is the most commonly used fuel for DRI, therefore biogas is a possible replacement, although it may have to be upgraded first. | '''Biogas''' -- methane from biogas can be turned into the H/CO mix. Globally, fossil gas (a.k.a. "natural" gas) is the most commonly used fuel for DRI, therefore biogas is a possible replacement, although it may have to be upgraded first (often contains sulfur compounds). | ||
'''Waste heat''' -- The DRI process generates waste heat that can be used for pyrolyzing biomass (pyrolysis = heating in | '''Waste heat''' -- The DRI process generates waste heat that can be used for pyrolyzing biomass (pyrolysis = heating in absence of oxygen). Pyrolysis releases more '''syngas''' which can be fed back into the process. Everything is thus powered by biomass, generating [http://openfarmtech.org/wiki/Biochar '''biochar'''] as a valuable by-product (permanently fixed carbon). In cold climates, any kind of waste heat can obviously be useful for heating winter greenhouses. | ||
'''[[Biochar]]''' -- is a charcoal-like soil amendment. It is resistant to biodegradation, i.e. it is carbon that has been permanently removed from the atmosphere. Some of the syngas that is released during pyrolysis could be used to make DRI. If these processes are combined, with biochar as a by-product, the whole thing becomes carbon negative. Biochar could be co-composted with spent slurry from a biogas digester, generating an excellent soil amendment. | '''[[Biochar]]''' -- is a charcoal-like soil amendment. It is resistant to biodegradation, i.e. it is carbon that has been permanently removed from the atmosphere. Some of the syngas that is released during pyrolysis could be used to make DRI. If these processes are combined, with biochar as a by-product, the whole thing becomes carbon negative. Biochar could be co-composted with spent slurry from a biogas digester, generating an excellent soil amendment. | ||
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A: This appears as a good alternative for smaller scale, lower-cost process, worth adding to our general awareness. | A: This appears as a good alternative for smaller scale, lower-cost process, worth adding to our general awareness. | ||
==Other Metals== | |||
*paper: [http://openfarmtech.org/w/images/c/c9/Halman.pdf Carbothermal reduction of alumina: Thermochemical equilibrium calculations and experimental investigation] | |||
*paper: [http://openfarmtech.org/w/images/c/c3/Lvov.pdf Mechanism of carbothermal reduction of iron, cobalt, nickel and copper oxides] | |||
==Internal links== | |||
* [http://openfarmtech.org/wiki/Metal_Refining Metal Refining] | |||
==External links== | ==External links== | ||
Revision as of 15:14, 23 January 2011
Direct-reduced iron (DRI) is a metallic material formed by the reduction (removal of oxygen) of iron oxide (iron ore) at temperatures below the melting point of iron. DRI is produced by the use of a reducing gas (mostly a mixture of hydrogen and carbon monoxide). The temperatures for this process are significantly lower than those in a blast furnace, and capital requirements are also lower. DRI may have a sponge-like structure, leading to the alternative name "sponge iron". Suitable starting materials are very high-grade iron ores (70% iron content and up) or rusted scrap steel, which is mostly iron. These could not be used in an induction furnace, as the reduction is a chemical reaction while induction only melts the already-reduced iron. India is one of the global leaders in sponge iron production, having numerous small or medium-sized facilities. DRI is commonly manufactured in a rotary kiln.
HDRI ("hot direct reduced iron"): moving the still-hot iron immediately for melting into an electric arc furnace or Induction_Furnace, to save energy.
Product ecology
Induction_Furnace -- could be fed with HDRI for energy-efficient steel production
Gasifier -- to create the reducing gas: syngas is a mixture of H and CO
Biogas -- methane from biogas can be turned into the H/CO mix. Globally, fossil gas (a.k.a. "natural" gas) is the most commonly used fuel for DRI, therefore biogas is a possible replacement, although it may have to be upgraded first (often contains sulfur compounds).
Waste heat -- The DRI process generates waste heat that can be used for pyrolyzing biomass (pyrolysis = heating in absence of oxygen). Pyrolysis releases more syngas which can be fed back into the process. Everything is thus powered by biomass, generating biochar as a valuable by-product (permanently fixed carbon). In cold climates, any kind of waste heat can obviously be useful for heating winter greenhouses.
Biochar -- is a charcoal-like soil amendment. It is resistant to biodegradation, i.e. it is carbon that has been permanently removed from the atmosphere. Some of the syngas that is released during pyrolysis could be used to make DRI. If these processes are combined, with biochar as a by-product, the whole thing becomes carbon negative. Biochar could be co-composted with spent slurry from a biogas digester, generating an excellent soil amendment.
Further information is needed !
- Is this actually feasible on the small scale ?
- Are we missing something here ?
- Does the process take place at normal atmospheric pressure ?
- Can a rotary kiln be designed for the village scale ?
- Are sufficient amounts of high-grade ores or rusted steel available ?
A: Scalability is feasible, but efficiency may not be as good. The processes of the largest plants can also be done on a table top. The question is - at what point does it still make sense to do so? If we have access to abundant energy, feasibility may occur at a village scale.
A: This appears as a good alternative for smaller scale, lower-cost process, worth adding to our general awareness.
Other Metals
- paper: Carbothermal reduction of alumina: Thermochemical equilibrium calculations and experimental investigation
- paper: Mechanism of carbothermal reduction of iron, cobalt, nickel and copper oxides
Internal links
External links
- Wikipedia: Direct Reduced Iron
- Wikipedia: Sponge Iron Reaction
- Wikipedia: Water Gas Shift => a way to increase the hydrogen content in syngas
- war-time 1942 TIME Magazine article on sponge iron