Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-07-24
1998-11-10
Kastler, Scott
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75444, 266142, 266156, 266172, C22B 514
Patent
active
058337342
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for the direct reduction of particulate iron-containing material by fluidization, wherein reformed gas, at least partially freed from CO.sub.2, is supplied to a fluidized-bed reduction zone as a reducing gas and is carried off from the same as a top gas and wherein at least a portion of the top gas together with reformed gas is utilized for direct reduction, and a plant for carrying out the process.
A process of this type is known from EP-A-0 571 358 and from U.S. Pat. No. 5,082,251. Here, iron-rich fine ore is reduced in a system of serially arranged fluidized bed reactors under elevated pressure by means of a reducing gas formed of natural gas by reforming. The iron powder thus produced is subsequently subjected to hot or cold briquetting.
With these known processes, in order to avoid too high a CO.sub.2 content in the reducing gas, the CO.sub.2 is eliminated from the reducing gas before introducing the latter into the first fluidized bed reactor, through scrubbing by means of a conventional CO.sub.2 scrubbing operation based on the principle of physical or chemical absorption. By the CO.sub.2 scrubbing, a high selectivity is achieved, i.e. predominantly CO.sub.2 and H.sub.2 S are removed from the gas stream that is to be purified. Other molecules, such as for instance H.sub.2, CH.sub.4, N.sub.2 etc., are practically not bound by the absorbent and persist within the purified gas stream. Natural gas is utilized for heating the reformer and, furthermore, for heating a reducing-gas heater, wherein optionally top gas is admixed.
The invention has as its object to further develop these known processes, namely in that, at constant reducing power, the volume of the reducing gas is to be decreased so as to enable savings in respect of all parts of the plant that are impinged on by the reducing gas. In particular, savings in terms of investment costs for the reducing-gas compressors and a reduction in the electricity consumed in compressing the reducing gas as well as savings with respect to heating costs are to be achieved, while the production capacity is at least to be kept equal or to be increased. Furthermore, it is to be feasible to employ the tail gas forming in the CO.sub.2 elimination plant in a manner that will be useful for the process.
With a process of the initially described kind, this object is achieved in that CH.sub.4 and N.sub.2 are, in addition to CO.sub.2, at least partially removed by adsorption, preferably by pressure-swing adsorption, either 50 to 100% of the reformed gas and 0 to 100% of the top gas, that the reducing gas is heated and that the tail gas removed from the reformed gas and/or the top gas by adsorption is utilized as a heating gas.
From DE-C-40 37 977 it is known per se to alternatively use a CO.sub.2 -scrubber or a pressure-swing adsorption plant for direct reduction in the direct reduction of lumpy iron ore. With this process, the lumpy iron ore is reduced in a reduction shaft furnace in the fixed bed method and on being yielded from the reduction shaft furnace is charged to a melter-gasifier in which the reducing gas fed to the reduction shaft furnace is produced from coal and oxygen and the reduced iron ore is melted. The process in question is a process that is carried out at low pressure, whereas with the fluidization process in accordance with the invention, the reducing gas is conducted at a pressure that is considerably higher. From this, a particular advantage results for the process according to the invention, namely that--in contrast to the known process--there is no need for additional compressors for conducting the gas to the adsorption process. Accordingly, substantial savings in terms of electric energy result for the fluidization process.
Compared to CO.sub.2 scrubbing, the adsorption process opens up the possibility of lowering the specific volume of the reducing gas while maintaining the same level of reducing power, due to the fact that with adsorption considerably larger amounts of CH.sub.4 and of inert N.sub.2 are sluice
REFERENCES:
patent: 2547685 (1951-04-01), Brassert et al.
patent: 3021208 (1962-02-01), Feinman
patent: 5082251 (1992-01-01), Whipp
patent: 5185032 (1993-02-01), Whipp
patent: 5192486 (1993-03-01), Whipp
patent: 5407179 (1995-04-01), Whipp
patent: 5439504 (1995-08-01), Czermak et al.
patent: 5531424 (1996-07-01), Whipp
patent: 5554206 (1996-09-01), Czermak et al.
patent: 5674308 (1997-10-01), Meissner et al.
Cip Gerhard
Milionis Konstantin
Rossmann Gottfried
Whipp, Jr. Roy Hubert
Brifer International Ltd.
Kastler Scott
Voest-Alpine Industriean-lagenbau GmbH
LandOfFree
Process for the direct reduction of particulate iron-containing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the direct reduction of particulate iron-containing , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the direct reduction of particulate iron-containing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1512500