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The Yield of iron oxide to DRI: Who cares? You Do!!!
Why should anyone care about the yield of iron oxide to DRI? A quick look at the graph shown below tells the story. The price of iron ore is dramatically higher than it has been at any time in the last 60 plus years. This graph shows the fob price of sinter fines coming out of Southern Brazil. Prices are shown since 1948 and they are adjusted for inflation to 2011 dollars. Sinter fines were chosen for the graph since they are transported in such large volumes that they comprise the bell weather grade for iron ores. Obviously, pellet prices are higher, with blast furnace grade pellets from Southern Brazil reaching 360 cents per dmtu* throughout the last three quarters of 2011. And, DR grade pellets are higher still; about 10% higher than blast furnace grade.
Of late, the price of ore has been three to six times higher than it had been at any time during the latter half of the 20th century. Prior to that only very small amounts of ore entered into long distance, trans-oceanic trade. It is clear that the quantity of ore needed to produce a ton of iron is extremely important to the economic success of an ironmaking plant. At some DR plants, the iron ore cost alone represents 90% of the total of all operating costs. That’s why we need to care about the yield of iron oxide to DRI.
Recently, some remarkable claims have been made by DR plant suppliers concerning how much ore is needed to make a ton of iron. Upon close examination, when the claims are ‘too good’, they’ve been calculated by looking at too small a system and one that is not relevant in the real world. For instance, if one were to ratio the amount of ore being fed into an ironmaking furnace to the amount of iron being produced, the ratio would be smaller than the ratio of the total amount of ore purchased compared to the amount of iron produced. After all, there will be some iron oxide losses during handling and screening.
When reading claims of remarkably efficient use of iron ore, one should beware. Obfuscation is rampant.
One point we would especially like to emphasize is that MIDREX® Plants generally meter the larger portion of screened oxide fines, usually those between 3 and 6 mm, back into the process stream of ore being fed to the reduction furnace. This allows the furnace to always operate at, or near, maximum productivity by never subjecting it to sudden surges of fines. Other processes claim that they only screen at the smaller size (for instance 3 mm). In either case, the plus 3 mm/minus 6 mm fines are charged to the furnace, but using Midrex’s technique, the furnace is not subject to the ‘slugs’ of fines that will be generated as stacks of iron ore are cleaned up; the fines go into the furnace at a relatively constant rate.
For more information on this topic, please refer to the article “How much iron ore is needed to make one ton of DRI?” in the 3&4Q 2011 Direct From Midrex.
posted by Robert Hunter
Tuesday, January 10, 2012 at 8:51 AM
Tuesday, January 10, 2012 at 8:51 AM
Why should anyone care about the yield of iron oxide to DRI? A quick look at the graph shown below tells the story. The price of iron ore is dramatically higher than it has been at any time in the last 60 plus years. This graph shows the fob price of sinter fines coming out of Southern Brazil. Prices are shown since 1948 and they are adjusted for inflation to 2011 dollars. Sinter fines were chosen for the graph since they are transported in such large volumes that they comprise the bell weather grade for iron ores. Obviously, pellet prices are higher, with blast furnace grade pellets from Southern Brazil reaching 360 cents per dmtu* throughout the last three quarters of 2011. And, DR grade pellets are higher still; about 10% higher than blast furnace grade.
Of late, the price of ore has been three to six times higher than it had been at any time during the latter half of the 20th century. Prior to that only very small amounts of ore entered into long distance, trans-oceanic trade. It is clear that the quantity of ore needed to produce a ton of iron is extremely important to the economic success of an ironmaking plant. At some DR plants, the iron ore cost alone represents 90% of the total of all operating costs. That’s why we need to care about the yield of iron oxide to DRI.
Recently, some remarkable claims have been made by DR plant suppliers concerning how much ore is needed to make a ton of iron. Upon close examination, when the claims are ‘too good’, they’ve been calculated by looking at too small a system and one that is not relevant in the real world. For instance, if one were to ratio the amount of ore being fed into an ironmaking furnace to the amount of iron being produced, the ratio would be smaller than the ratio of the total amount of ore purchased compared to the amount of iron produced. After all, there will be some iron oxide losses during handling and screening.
When reading claims of remarkably efficient use of iron ore, one should beware. Obfuscation is rampant.
One point we would especially like to emphasize is that MIDREX® Plants generally meter the larger portion of screened oxide fines, usually those between 3 and 6 mm, back into the process stream of ore being fed to the reduction furnace. This allows the furnace to always operate at, or near, maximum productivity by never subjecting it to sudden surges of fines. Other processes claim that they only screen at the smaller size (for instance 3 mm). In either case, the plus 3 mm/minus 6 mm fines are charged to the furnace, but using Midrex’s technique, the furnace is not subject to the ‘slugs’ of fines that will be generated as stacks of iron ore are cleaned up; the fines go into the furnace at a relatively constant rate.
For more information on this topic, please refer to the article “How much iron ore is needed to make one ton of DRI?” in the 3&4Q 2011 Direct From Midrex.
