Solid material comminution or disintegration – Processes – By operations other than force of contact with solid surface
Reexamination Certificate
1999-06-29
2001-03-06
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
By operations other than force of contact with solid surface
C241S005000, C241S024140, C241S039000, C241S023000, C241S065000, C241S079000, C241S301000
Reexamination Certificate
active
06196479
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is relates to a method for granulating and comminuting liquid slags, especially slags containing metal oxides such as, e.g., converter slags or refuse-incineration slags, mixtures of steel- and blast-furnace slags or non-ferrous metallurgic slags, e.g., Cu— or Ni slags as well as to a device for carrying out this method.
2. Description of the Related Art
In an older development of the applicant (GM 94/98) a method already has been disclosed for granulating and comminuting liquid slags in which method pressurized water was driven into the slag melt, especially for the comminution of liquid blast-furnace slags, and the slag brought as a surface of the jet of pressurized water into a grinding chamber. With this method the direct conversion of the internal energy and especially of the perceptible heat of slag melts into grinding operations was directly utilized; however, the older suggestion, in which only water was driven in under high pressure, has a number of limitations with regard to the selection of the slags to be granulated and comminuted. The older method was basically suited primarily for the comminution of blast-furnace slags with only slight amounts of metals or metallic particles produced during the granulation. Blast-furnace slag to be granulated generally has a low amount of residual raw iron which is below 0.5% by weight if the method is carried out properly on the other hand, slags containing metal oxide or iron oxide such as converter slags have considerably greater amounts of residual raw iron and/or readily reducible iron oxides which, in conjunction with water as granulation medium, might bring pose a danger of exploding due to the formation of hydrogen gas. It was therefore suggested for this reason in the older method that the liquid slags be completely oxidized by introducing oxygen in order to increase safety and to saturate the liquid slags with gases in order to improve the communution action.
SUMMARY OF THE INVENTION
Based on this principle of slag microgranulation, which allowed a high degree of rapid comminution to be achieved by means of a sudden expansion of the water core and of the gases dissolved in the slags, the present invention serves to extend the area of application of the principle of the method to any slags and especially to slags containing metal oxides such as, e.g., converter slags or refuse-incineration slags, without taking the risk of oxyhydrogen explosions. The method of the invention is particularly suitable for highly basic slags, which exhibit a strong tendency to devitrify, in the case of which an especially rapid cooling off is necessary in order to maintain the glass structure and should also be able to be used for acidic systems, e.g., fayalithic slag melts.
In order to solve the problem of the invention the method of the invention resides in that the liquid slag is directed into an expansion chamber or granulating chamber, that coal, hydrocarbons, CO
2
-containing gases and/or coal/water mixtures or coal slurries are introduced into the liquid slag or into the slag jet and are converted at least partially to CO and H
2
, during which the slag droplets are reduced and cooled, and that the dust mixture of clinker dust and slag dust and metal dust is separated from each other, e.g., by magnetic separation. As a result of the fact that now hydrocarbons or coal/water mixtures are used instead of pure water a strongly reducing atmosphere is created with the energetic advantages of the known method being preserved unchanged. If high-pressure heavy oil or diesel oil or old solvents are used a rapid dissociation or a cracking of the hydrocarbons used occurs during the high-temperature reaction with the liquid slag which results in an especially rapid cooling off of the liquid slag. On the whole, a pyrolytic decomposition of the hydrocarbons takes place thereby which results at the same time in an at least partial reduction of slag. Even when using coal/water mixtures in CO
2
suspended coal dust or coal slurries the reducing portion predominates, which portion is assured by the coal content in order to reliably prevent the danger of explosions. At the same time the reducing atmosphere formed during the forcing in [injecting] of coal slurries permits the reducing of metal oxides from metal-oxide-containing slags. In the case of high-pressure hydrocarbons such as, e.g., heavy oils or the like carbon monoxide can be formed by additionally bringing in oxygen and/or water, during which a reducing atmosphere continues on the whole to remain.
The gasification reaction in the crack/gasification chamber acts, so to speak, as a combustion chamber and the propellant gas formed (C+H
2
O→CO+H
2
) accelerates the slag granulate. An addition of water in such a combustion chamber, in which only a partial combustion takes place, directly permits the formation of synthesis gas and water gas. At the same time, with a rapid cooling off and disintegration under formation of especially fine-grained solids a reduction of slag can thus be carried out and formed metal dust separated off.
The method in accordance with the invention is advantageously carried out in such a manner that hydrocarbons in the form of a jet of heavy oils, diesel oils or old solvents under a pressure of above 15 bar, especially 30 to 260 bar are used. It is advantageous if high-pressure water is driven alternately or simultaneously with coal dust or hydrocarbons into the liquid slag.
A method is particularly advantageous here in which water vapor or CO
2
is driven in under a pressure of 3 to 30 bar coaxially to the mouth of the slag exit and the slag jet is charged after leaving the mouth with carbon carriers, especially coal and pressurized water, or coal dust fluidized in CO
2
. In such a method high shear forces act on the slag jet without an appreciable cooling off by the vapor taking place; the subsequent charging of carbon yields the desired gasification and the desired, rapid solidification by means of the pressurized water applied.
As already mentioned, carbon monoxide can be formed by the additional introduction of oxygen, CO
2
and/or water. It is preferable to proceed in such a manner to this end that the slag jet is charged with O
2
, CO
2
and/or H
2
O for developing CO and CO+H
2
and that the granulated slag is introduced together with the CO or cracked gas formed into the grinding chamber of a jet mill or impact mill. CO
2
is converted thereby with C to CO.
An especially good comminution and a valuable end product can be achieved in that the slags are adjusted to a basicity (CaO/SiO
2
) between 0.2 and 3.8, especially 2.8 to 3.6 and are introduced with this basicity.
In order to improve the thermal efficiency the driving out of the liquid slags can take place with hot waste combustion gases. Superheated water vapor with temperatures of above 1200° C., especially 1450° C., is preferably used to atomize the liquid slags.
The reduction of the atomized slags is preferably carried out thereby at temperatures of 600° C. to 1600° C. in a fluidized bed.
With regard to the metal dust being produced the cooled dusts are preferably cooled off under an inert atmosphere to below 100° C. Preferably carbon in an amount of 250 to 300 kg/t slag is introduced into the cooling chamber for the reduction.
In an especially preferred device for carrying out the method with a slag tundish and a lance arranged coaxially to the axis of the tundish tube, the tundish tube being designed as a hole-type nozzle, and devices for applying carbon carriers and/or water jets are arranged radially outside of the mouth of the tundish tube. If necessary, the comminuted product can be subsequently ground in a conventional manner.
On the whole, carrying out the method of the invention makes it possible to significantly reduce the consumption of water during the granulating of liquid slags or to eliminate it if CO
2
/C is used and at the same time to carry out reduction work.
REFERENCES:
patent: 4909821 (199
Pillsbury & Winthrop LLP
Rosenbaum Mark
“HolderBank”Financiere Glarus AG
LandOfFree
Method and device for granulating and comminuting 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 Method and device for granulating and comminuting liquid slags, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for granulating and comminuting liquid slags will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2491532