Metallurgical apparatus – Means for melting or vaporizing metal or treating liquefied... – Slag refining means
Reexamination Certificate
2002-03-06
2004-10-12
Andrews, Melvyn (Department: 1742)
Metallurgical apparatus
Means for melting or vaporizing metal or treating liquefied...
Slag refining means
C241S065000, C264S012000, C425S007000
Reexamination Certificate
active
06803016
ABSTRACT:
The invention relates to a device for atomizing and granulating liquid oxidic slags such as, e.g., converter slags, blast furnace slags or waste incineration slags, including a slag tundish having an outlet opening into which a height-adjustable lance for a propellant jet opens and to which a cooling chamber is connected, said outlet opening being surrounded by an immersion tube arranged concentrically therewith while forming an annular gap.
From AT 406 262 B a method for spraying oxidic slags became known, in which liquid slag was ejected from a tundish via a tundish tube, wherein a lance was introduced into the liquid slag to inject a propellant gas and, in particular, water vapor. The tundish tube provided in the slag outlet of the tundish as illustrated in AT 506 262 B could also be designed in the manner of a Laval nozzle, whereby vapor flow velocities in the supersonic range were observed, too, both due to the supercritical conditions under which hot vapor or water vapor was supplied and due to the subsequent possibility of a rapid expansion. In that known device a slag melt having temperatures of between about 1300° and 1500° C. was, thus, ejected using hot vapor as a propellant, rapid cooling having been effected subsequently within the cooling chamber by the reaction of carbon or carbon carriers with water vapor and the slag heat to carbon monoxide and H
2
, thus providing reducing conditions. The propellant vapor jet tube was oriented coaxially with the tundish outlet opening. In principle, such a device allows for only limited controlling options and, in particular, involves an extremely high consumption of propellant gas as well an extremely high consumption of coolant with a high amount of gas being required and a high amount of gas being formed said by reaction.
From WO 00/32306 it became known, in addition, to conduct an immersion tube or throttle tube concentrically with the tundish outlet in an immersed manner, the lower edge of that throttle tube having been mounted so as to be adjustable in the height direction. By means of such a throttle tube, it was feasible to appropriately adjust the thickness of the jacket of the tubularly emerging slag jet, yet the propellant jet was substantially injected in a axial direction also there. By the aid of the throttle tube, the direct immersion of the lance into the slag could, however, be avoided, since the propellant jet lance was guided in the interior of the throttle tube. The comminution forces in such a configuration basically enter into effect as shearing forces by a substantially axially directed propellant jet with an appropriate viscosity inducing an acceleration, and hence appropriate shearing forces, after its expansion in the interior of the liquid slag jacket concentrically surrounding said propellant jet. Since the viscosity of gases increases at increasing temperatures, extremely hot vapor was used to ensure high shearing forces and hence an adequate comminution effect. The comminution performance could even be enhanced in that the throttle tube was designed to be closed by a lid and a throttled gas-feed duct ran into the throttle tube. On account of suitable pressure conditions developing within the annular space provided around the lance, resonance effects could be utilized while obtaining accordingly pulsating jets with periodic pressure bursts, thus improving droplet comminution.
Since the shearing forces enter into effect primarily because of the axial acceleration, the consumption of propellant is relatively high, and the overall structural height of the device is relatively large, also in that embodiment.
The invention aims to improve a device of the initially mentioned kind to the extent that a substantially reduced propellant gas feed will do while, at the same time, an enhanced comminution performance leading to even finer particle sizes is ensured in a substantially shorter-structured device. To solve this object, the device according to the invention essentially consists in that a guide body capable of being adjusted in the axial direction of the lance is arranged in the region of the nozzle mouth of the lance for the propellant jet, which guide body deflects the propellant jet in the radial direction. By arranging a guide body capable of being adjusted in the axial direction of the lance in the region of the nozzle mouth of the lance it is feasible to deflect the propellant jet from a substantially axial direction into a more or less radial direction, thus substantially reducing the free distance until its impingement on the slag jacket. The device advantageously may be operated in a manner that the propellant jet is fed under supercritical conditions so as to cause its rapid expansion after having left the nozzle, by which the propellant jet is accelerated to supersonic speed. Such a propellant jet accelerated to supersonic speed will then collide with the liquid jacket of the outflowing slag already after an extremely short distance, thus ensuring a particularly efficient comminution performance.
An essential criterion for the proper functioning of a device of this kind resides, of course, in the control of the solidification and corrosion processes in order to adequately observe the respectively desired parameters relating to the geometry of the jet and the thickness of the emerging slag jacket. The used slags and, in particular, converter slags, as a rule, are characterized by relatively high iron oxide contents, thus involving considerable refractory problems. A suitable protection of the structural components that get into contact with such slags may usually be obtained only by the formation of a precisely defined slag pelt, to which end various ways of adjustment and setting must be made available in order to safely control also the growth of such a slag pelt to the minimum extent desired. Due to the relatively fine comminution provided by the semi-radially directed propellant gas jets impinging on the slag jacket at supersonic speed, it is to be considered further that, in addition to the physical comminution, also chemical processes occur in an accelerated manner on account of the relatively large specific surfaces of these small solidifying particles. As already proposed, particularly rapid cooling is feasible by the chemical reaction of the hot slag jet and the propellant vapor with carbon carriers such as, for instance, hydrocarbons, thus forming carbon monoxide and hydrogen.
Due to the small particle size, a relatively large portion of iron powder having an extremely small particle size is, thus, formed in the product obtained such that operation should be continued under reducing conditions also for this reason in order to avoid the spontaneous ignition of such most finely distributed iron particles. These most finely distributed iron particles, or iron powder, in turn, constitute a high-quality product, which will substantially enhance the economy of the method if successfully discharged without involving any risk of reoxidation. Advantageously, the method according to the invention is, therefore, controlled to proceed in a reducing manner, wherein the configuration of a device suitable for that purpose advantageously is devised such that coolant outlets which are directed radially inwards are arranged concentric with the slag jet in the region of the outlet opening or immediately following the outlet opening. Such additional radially inwardly directed coolant outlets allow the device to be operated in a manner that also the coolant is supplied under supercritical conditions so as to rapidly expand, and also accelerate to supersonic speed, after having left the nozzle. The substantially tubular slag jacket emerging from the tundish, thus, is powered in the radial direction not only from inside by the propellant jet particles expanding at supersonic speed, but also from outside by the coolant particles expanding at supersonic speed, so that a particularly efficient comminution with simultaneous cooling under the formation of particularly fine particles will be ensured. Due to t
Andrews Melvyn
Chapman and Cutler LLP
Tribovent Verfahrensentwicklung GmbH
LandOfFree
Device for atomizing and granulating liquid slags does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for atomizing and granulating liquid slags, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for atomizing and granulating liquid slags will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3272757