Glass manufacturing – Processes – Slag – utilization
Patent
1986-12-02
1988-07-19
Lindsay, Robert L.
Glass manufacturing
Processes
Slag, utilization
65141, 75 24, C03B 1900
Patent
active
047582600
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process for the production of slag sand (granules) from blast-furnace slag by granulation of the slag by means of jetting water in a spray head into the slage jet, the resulting granules/water mixture being dewatered in a downstream dewatering unit, the granules being fed to a distribution unit and the process water, after making up the losses caused by vaporization and the residual moisture remaining in the granules, being recycled to the spray head and the vapours and gases formed on granulation being collected in a space above a granules/water mixture receiver, and to advantageous equipment for carrying out the process.
It is known that, in the conversion of iron ore to crude iron in a blast-furnace, blast-furnace slag is formed to a considerable extent in addition to the molten crude iron. On each tapping, a quantity of slag is formed, the weight of which corresponds to approximately one third of the weight of the crude iron, whereas the volume fraction of the slag, because of the lower density of the slag, is greater than the volume fraction of crude iron.
Various processes are known for producing high-grade granules with a high percentage of glassy constituents, uniform grain structure and good grindability from blast-furnace slag by granulation of the molten slag directly at the blast-furnace. The granules formed can then be put into intermediate storage for further processing into building materials and transported away.
An important step in the processing of the granules is dewatering. For this purpose, various processes and types of equipment are known (German Patent Specification No. 1,583,949, German Patent Specification No. 2,260,924) as well as modern dewatering machines with bucket wheels, wherein the slag sand/water mixture is dewatered to a low residual moisture content and the process water is recycled for reuse (German Offenlegungsschrift No. 2,749,143, German Offenlegungsschrift No. 2,807,441 and German Offenlegungsschrift No. 2,911,903). In these known processes, the slag granulation was effected by spraying the molten slag at about 1500.degree. C. by means of a propulsion jet, consisting of many individual jets, from a spray head at a temperature of 35.degree.-40.degree. C. and thus processing it to give fine granules. The water vapour arising in this process contains large quantities of H.sub.2 S and H.sub.2 O, in particular when sulphur-containing ores are used. The fractions of the pollutants H.sub.2 S and SO.sub.2 contained in the water vapour formed on quenching of the slag have hitherto been discharged in the vapour via a stack.
SUMMARY OF THE INVENTION
By contrast, it is the object of the invention to develop a process of the type explained above in such a way that the fractions of the pollutants H.sub.2 S and SO.sub.2 are separated off or dissolved in the water.
According to the invention, this object is achieved essentially in such a way that the water propulsion jet is introduced directly into a water receiver, that vapours and gases thus arising are partially condensed in the water receiver and the residual vapour and the residual gases are sprayed with water and thus condensed, and that the residual gases then still remaining are recycled back to the spray head.
As a result of the measures according to the invention, the propulsion jet with added water vapour gases and granules is sprayed directly into a large water receiver. The impulse introduced into the water receiver with the propulsion jet then ensures intensive mixing and at the same time improved heat release. In a condenser above the water receiver, the residual vapour still remaining and the H.sub.2 S and SO.sub.2 pollutants not yet washed out are cooled in counter-current with spray water and condensed, absorbed by the water and transferred to the lime present in the cooling water in conjunction with an oxidation potential. The water jetted into the condenser is, in conjunction with the absorbed pollutants from the vapours and gases, fed via a pumping st
REFERENCES:
patent: 3695004 (1972-10-01), DeLisio et al.
patent: 3738820 (1973-06-01), Osborne et al.
patent: 3912487 (1975-10-01), Sharanov et al.
patent: 4209313 (1980-06-01), Lynn et al.
Suzuki, Patent Abstracts of Japan, vol. 2, No. 43, Mar. 23, 1978, p. 4953 C 77.
Geropp Dieter
Muller Konrad
Wiedemer Karl
AJO Stahlbau GmbH & Co. KG
Lindsay Robert L.
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