Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Patent
1995-08-18
1998-06-30
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
75414, 75460, C21B 502
Patent
active
057727279
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for the production of metal from metal ores, particularly of pig iron from iron ore, in which the ore containing metal oxides is brought to a reaction contact with a reducing gas containing carbon and/or hydrogen (and possibly also their compounds), the gas having been previously obtained from substances containing carbon and/or hydrocarbons.
BACKGROUND OF THE INVENTION
It is customary that ore consisting mainly of metal oxides (even other than oxides of iron) must be subjected to a reduction process before the metal can be extracted. This reduction is carried out with the help of carbon and possibly hydrogen--or also their compounds--which are contained in a reducing gas, which is used to act on the metal ore.
After that, the reduced metal ore is subjected to a melting process. The gas needed for the reduction is obtained within the region of the reduction and melting processes themselves in that carbon containing substances (e.g. coke, coal, oil, or natural gas) are added to the zone of the already reduced and heated metal whereby, with the addition of oxygen, or oxygen from air, decomposition or conversion into carbon-containing gas follows, and this is supplied for the preceding reduction.
In this respect are known the conventional blast furnace process. In this process, the reduction of the metal ore and the generation of the reducing gas and also the final melting of the metal to a liquid state all take place in the blast furnace, continuously from top to bottom. In the blast furnace process coke is added as a carbon carrier to the iron ore and possible admixtures. It is also known, for a better control of the blast furnace process and in order to save coke, to inject through lances, into the blast current, oil or pulverized coal, which reduces consumption of coke. This additionally injected material (oil or pulverized coal) must be introduced in a finely comminuted state to ensure clean and sufficient gasification. Summaries about the injection of pulverized coal into blast furnaces are contained in two articles in the magazine "Stahl und Eisen", 101 (1981) of 12.1.81, p. 35-38 and 105 (1985), no. 4 of 25.2.85, p. 211-220. The injection of pulverized powder was stepped up particularly during the increasing oil prices. It was found that during injection, due to the short time of about 10 ms which was available, good results, i.e. complete gasification of the pulverized coal, were obtained only with grain sizes below 0.1 mm, although experiments were made in some plants also with larger grain sizes.
It has already been suggested to introduce, instead of the injection of oil or pulverized coal, other carbon-containing waste materials, such as refuse, waste paper, straw, lignite and also waste wood, plastics, rubber and similar material (DE-A-29 35 544). In the absence of corresponding experiments or results only suppositions were made regarding how the substances should be introduced into the blast furnaces. Suggests the injection of carbon-containing refuse of this kind through tuyeres in fine-grained or powder form into a blast furnace, while the introduction of sedimentation sludge (flowable dust) was given as an example. Also in this process the necessity was stressed that the substance to be injected should be fine-grained.
SUMMARY OF THE INVENTION
Starting from the initially described known process, it is the aim of the invention to utilize, as a source of components for the reducing gases, plastics refuse even if it is organically and/or inorganically contaminated. Plastics refuse is always available in large quantities and represents a serious waste disposal problem. It is available mostly, though not exclusively, in solid form either as packaging waste--often heavily contaminated--or as scrap or similar waste obtained during the production of plastics articles.
Consequently the invention provides that in a process of the initially mentioned kind, substances containing carbon and/or hydrocarbons supplied to generate the reducing g
REFERENCES:
patent: 3876421 (1975-04-01), Takemura
patent: 3955966 (1976-05-01), Meichsner
patent: 3998606 (1976-12-01), Miyashita et al.
patent: 5244490 (1993-09-01), Agarwal
patent: 5554207 (1996-09-01), Bogdan et al.
de Haas Hans
Janz Joachim
Mohnkern Horstmar
Voss Manfred
Andrews Melvyn
Stahlwerke Bremen GmbH
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