Specialized metallurgical processes – compositions for use therei – Processes – Producing solid particulate free metal directly from liquid...
Patent
1998-10-16
2000-11-14
Mai, Ngoclan
Specialized metallurgical processes, compositions for use therei
Processes
Producing solid particulate free metal directly from liquid...
B22F 906
Patent
active
061464392
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for producing atomized metal powder in an atomization plant comprising a casting box, a reactor vessel, a powder container and sedimentation equipment. The invention also relates to the atomization plant, atomized metal powder produced according to the process and the use of the metal powder.
One of the problems in manufacturing atomized metal powder is that the thermal balance in the reactor is not in balance and that critical temperatures occur. This entails increased risk of explosion since the firing temperature and partial pressure are reached in uncontrolled manner.
Another problem is that if the pressure of the spray coolant is too high the powder particles will be deformed, becoming uneven and pointed in shape. High temperature of the spray coolant also causes the formation of waves on the surface of the liquid.
The object of the present invention is to provide a solution to these problems. According to the invention they are solved by introducing atomizing medium into the reactor vessel via primary nozzles in the upper part of the reactor. Coolant is then supplied at low pressure via at least one secondary supply arrangement in the upper part of the reactor vessel, arranged in combination with the nozzles for atomizing medium. Coolant and atomizing medium are withdrawn from the lower part of the reactor and then recirculated via a number of transport arrangements and sedimentation equipment. Some of the metal powder is removed directly from the reactor, down into a powder container. The rest of the metal powder is separated through sedimentation in sedimentation equipment.
The embodiment described above, and other embodiments of the invention, are defined in the dependent claims.
Another embodiment of the present invention is the use of atomized metal powder as coolant in the manufacture of steel.
A further embodiment of the present invention is the use of the metal power for the manufacturing of tool steel.
A further embodiment of the present invention is the use of the metal power as additive in steel powder mixtures for powder-metallurgy production in a content of approximately 10%.
A further embodiment of the present invention is the use of the metal power having a particles size less than 150.mu. as additive in steel powder mixtures for powder-metallurgy production.
DESCRIPTION OF THE INVENTION
From a casting box a stream of molten metal, preferably steel, flows into the reactor vessel. The stream is disintegrated by atomizing medium flowing under high pressure from primary nozzles in the upper part of the reactor. Secondary coolant is allowed to flow under low pressure from at least one annular extruder in connection with the primary nozzles. The coolant flows down through the gas chamber of the reactor vessel and forms cooling curtains. The gas-filled part of the reactor is therefore smaller than the corresponding gas chamber in conventional atomizing plants. Large quantities of coolant at low pressure achieve efficient cooling of the powder particles without them become deformed. They retain their spherical shape since the thrust with which the coolant encounters the particle surface is limited. The desired final product is thus obtained and at the same time the thermal balance necessary for safety of the process is also achieved. Wave formation is greatly suppressed through the supply of secondary coolant through the annular extruders and the variation in the path of the powder particles from vortex to liquid surface is thus reduced.
In order to attain constant conditions in the reactor vessels the coolant balance must be at equilibrium during the atomizing period. The same amount of coolant must be removed from the reactor vessel as is supplied during the same time period. The falling rate of metal powder with a size of 100.mu. is in the order of magnitude a few cm/sec. So that the reactor plant does not become unreasonably large the bottom of the reactor vessel has been provided with an inner cone so that the powder formed is guided down thr
REFERENCES:
patent: 4025249 (1977-05-01), King
patent: 4124377 (1978-11-01), Larson
patent: 4224260 (1980-09-01), Dain et al.
patent: 4437891 (1984-03-01), Umino et al.
patent: 4770718 (1988-09-01), Verhoeven et al.
patent: 4810284 (1989-03-01), Auran et al.
patent: 4822267 (1989-04-01), Walz
patent: 4919854 (1990-04-01), Walz
patent: 4999051 (1991-03-01), Yolton et al.
patent: 5196049 (1993-03-01), Coombs et al.
patent: 5609799 (1997-03-01), Shima et al.
patent: 5749938 (1998-05-01), Coombs
Axmin Erik
Larsson Rutger
Mai Ngoclan
Rutger Larsson Konsult AB
LandOfFree
Process and plant for producing atomized metal powder, metal pow 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 and plant for producing atomized metal powder, metal pow, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and plant for producing atomized metal powder, metal pow will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2061337