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Showing posts with label ROMELT. Show all posts
Showing posts with label ROMELT. Show all posts

ROMELT - Another No Coke Alternative Smelting Reduction (SR) Process of Ironmaking

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ROMELT - The Process
This process was developed by the Moscow Institute of Steel and Alloys (MISA) in the mid-eighties to produce liquid iron from iron-bearing ores (lumps and fines) as well as waste iron oxides generated in an integrated plant using non-coking coal and oxygen. ROMELT is the only single stage SR process.
Unlike COREX and most other SR processes, the strength of this process is that it is a single stage concept. That is why ROMELT is a robust and simple process, which is also very much environment-friendly, since it operates under a slight negative pressure. As a result the area around a ROMELT plant is extremely clean. However, the process has a few inherent weaknesses being a single stage process, it uses large amounts of coal (1.3 - 1.5 t/thm) as well as oxygen (1100 - 1200 Nm3/thm) and it generates a very rich exit gas, which has to be utilized effectively e.g. in power generation to meet the demand of oxygen plant to make the hot metal production economic.        
ROMELT Process - The Advantages
=> This process can accept iron ore in a wide range of sizes (0 - 20 mm) without any pre-treatment. This would allow operating units to use slimes and other iron-bearing wastes which can be a big advantage for many reasons.
=> Non-cocking coals of size 0 - 20 mm with moisture content less than 10% are acceptable for this process. Although it is preferable to restrict the VM content of the coal up to 20%, higher VM coals can also be used. Then, no separate coal preparation is required.
=> The ROMELT process is capable of achieving fairly high degrees of post-combustion (even more than 70%) of the melter gas (primarily CO and H2) before it leaves the reactor, thus ensuring satisfactory utilization of energy even though it is a single stage process.
=> The quality of ROMELT iron is excellent - Carbon 4%, Silicon 0.6%, Manganese 0.05%, Sulphur 0.04% and temperature 1400 - 1450OC. The process offers particular advantage  in terms of phosphorous in hot metal because in the ROMELT process, instead of 100% phosphorous going to metal (as is the case in Blast furnace), only 60% phosphorous is reported to be in the hot metal while 30% goes to the slag, and 10% forms a part of exit gas.
=> Small scale production of 200000 to 1000000 tpa of hot metal is possible along with flexibility in production. The capacity of the rectangular ROMELT reactor (productivity in the range of 0.95 t/m2 of hearth area) is limited by the penetration of oxygen from the side-wall tuyeres into the bath. Thus, ROMELT unit may be ideal for supplying hot metal in EAF based mini steel plants.
=> The specific investment in a ROMELT plant is not likely to be as high as in many other SR processes because the equipment is simple and easy to operate. For the same reason, the plant availability should be high.