Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
1999-06-14
2001-08-14
Kastler, Scott (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S500000, C266S216000, C266S197000
Reexamination Certificate
active
06273933
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for injecting metal-oxide-containing fine particles into a reducing gas, as well as to an arrangement for carrying out the process.
The process of introducing fine ore particles into a reducing gas duct and of reducing the ore particles during transport in the reducing gas duct is known (JP-A-62-164569). According to JP-A-62-164569, the fine ore is sucked into the reducing gas stream via a nozzle. Herein, the problem arises that the reducing gas cannot come into optimum contact with the individual metal-oxide-containing fine particles.
The fine particles entering the reducing gas stream form a compact material stream even if they are injected into the reducing gas stream by means of a carrier gas. Only after a certain distance has been covered is the material stream fanned so that only a smaller distance and, thus, only less time is available for reduction. Another disadvantage is that the material stream, due to its compactness resulting from its entering the space accommodating the reducing gas, may cause wearing of the wall delimiting said space by abrasion.
The object of the invention is to avoid these disadvantages and difficulties and to solve the technical problem of creating a process of the type described above as well as an arrangement for carrying out the process allowing to ensure an optimum contact of the individual fine particles with the reducing gas immediately after the metal-oxide-containing fine particles have entered a space accommodating the reducing gas so that each fine particle is enclosed by reducing gas, immediately after exiting the duct feeding the fine particles. This is to enable the chemical, physical and thermal reactions, which all take place starting from the surfaces of the fine particles, to proceed immediately after introduction of the fine particles into the space accommodating the reducing gas so that the time during which the fine particles are staying in this space can be optimally used. This is also to allow a minimization of the arrangement for direct reduction and an optimum utilization of the reducing gas.
SUMMARY OF THE INVENTION
According to the invention, this problem is solved by feeding a central material stream formed by the fine particles and a carrier gas into the reducing gas and by directing at least one gas stream formed by a secondary gas against the material stream, the gas stream atomizing the material stream and the fine particles being evenly distributed within the reducing gas.
The gas stream preferably imparts to the material stream a moment of rotation about the axis of the material stream, the fine particles exit from the material stream by the centrifugal forces and the latter is dispersed.
The effect of utilizing the centrifugal forces can be even intensified by the gas stream imparting to the material stream periodically fluctuating moments of rotation, preferably of different dimensions, which also allows to find the optimum moment rotation.
The gas stream is expediently directed against the material stream askew and in such a manner as to intersect the material stream and only penetrates the outer zones of the material stream, angle &agr; between the gas stream and the material stream being periodically variable.
The gas stream is advantageously formed by inert gas, but also a reducing gas can be used therefor.
According to a preferred embodiment, the reducing gas flows past the material stream, i.e. the material stream is injected into a reducing gas stream, the material stream being expediently oriented in a direction opposite to the direction of flow of the reducing gas, preferably at an angle ranging between 100° and 160°.
Preferably, at least one gas stream is directed against the center of the material stream and penetrates the latter.
The process according to the invention can be particularly advantageously used for a reduction process characterized in that the material stream is fed into a reducing gas stream that departs from a meltdown gasifying zone in which a reducing gas containing CO and H
2
is formed by coal gasification and in which partially and/or completely reduced metal-containing particles are completely reduced or melted, respectively, and said reducing gas stream, after the material stream has entered, is subjected to solids separation and subsequently reacted in a reduction zone under reduction of a metal-oxide-containing ore, the fine particles separated during solids separation being supplied to the meltdown gasifying zone via a dust burner effecting an agglomeration of the fine particles.
An arrangement for carrying out the process according to the invention is characterized by the combination of the following characteristic features:
a space delimited by a wall for receiving a reducing gas,
an injection nozzle entering the space through the wall,
which is provided with a central pipe conducting fine particles and a carrier gas and,
at the mouth of the central pipe, is provided with at least one nozzle connected to a gas duct for feeding a secondary gas, wherein
the longitudinal axis of the nozzle encloses an angle &agr; with the longitudinal center line of the central pipe, which ranges preferably between 20° and 60°.
According to a preferred embodiment, the longitudinal axis of the nozzle is oriented askew relative to the longitudinal center line of the central pipe, wherein, if the longitudinal axis of the nozzle is projected perpendicularly onto a plane laid through the longitudinal center line of the central pipe and the nozzle mouth, an angle &agr; ranging between 20° and 60° is formed between the projected longitudinal axis of the nozzle and the longitudinal center line of the central pipe.
In this arrangement, the nozzle is expediently movably arranged at the mouth of the central pipe and, with its longitudinal axis, is capable of assuming different positions, preferably different askew positions, relative to the longitudinal center line of the central pipe.
For atomizing the material stream, it may be advantageous under certain local circumstances if several nozzles are arranged only at one half of the circumference of the mouth of the central pipe.
For material streams of larger volumes, several nozzles are expediently arranged over the entire circumference of the mouth of the central pipe in such as way as to be distributed approximately evenly.
A preferred variant is characterized in that the space for the reducing gas is formed by a pipe conducting the reducing gas, into which the injection nozzle opens from the side, the longitudinal center line of the injection nozzle and the center line of the pipe conducting the reducing gas expediently including an angle ranging between 100° and 160°.
The longitudinal axis of at least one nozzle preferably intersects the longitudinal center line of the central pipe.
A preferred application of the arrangement according to the invention is characterized in that the arrangement opens into a gas discharge pipe departing from a melter gasifier for melting and optionally completely reducing metal ores as well as for producing a reducing gas containing CO and H
2
by coal gasification and the gas discharge pipe opens into a solids separator, such as a cyclone, from which the solids separated in the solids separator can be recircled into the melter gasifier via a solids recircling duct and a dust burner.
REFERENCES:
patent: 4147535 (1979-04-01), Lilja et al.
patent: 4490170 (1984-12-01), Lilja et al.
patent: 5226951 (1993-07-01), Kepplinger et al.
patent: 5714113 (1998-02-01), Gitman et al.
patent: 470622 (1929-01-01), None
patent: 827957 (1960-02-01), None
patent: 60-209430 (1985-10-01), None
patent: 90/15162 (1990-12-01), None
Brandl Peter
Gennari Udo
Hauzenberger Franz
Kepplinger Leopold Werner
Nagl Michael
Kastler Scott
Ostrolenk Faber Gerb & Soffen, LLP
Voest - Alphini Industrieanlagenbau GmbH
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