Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Patent
1991-10-08
1992-06-30
Andrews, Melvyn J.
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
75384, 75385, 75644, 75696, 75561, 75567, C21D 1100
Patent
active
051259630
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a method for monitoring and controlling of smeltmetallurgical, endothermic and exothermic processes, particularly pyrometallurgical processes by means of optical spectroscopy.
The object of the present invention is to obtain a possibility to control different smeltmetallurgical, endothermic and exothermic processes, particularly pyrometallurgical processes by spectrophotometry in a simple and rational way thus making it possible to improve the yield of the processes in a qualitative and quantitative way.
2. Background of the Invention
In pyrometallurgy, such as copper production, lead production, and iron and steel production fire and flames are generally encountered. The visual observation of these flames has for a long time been used to judge if and when such a process is to be interrupted or the running mode to be changed in any other way. In doing so one has then more or less on a firm ground supposed, that the process has reached a certain stage, phase or temperature as the flames have changed their colour, or seemingly have changed their color.
In iron production certain quantitative methods of analysis are in use, whereas in the copper production on-line methods are not in use to the same extent. Particularly the copper converting process uses purely visual methods for process control. In particular during the slag blowing phase and the production of blister copper it is important that the process is interrupted at the correct moment. An incorrect blowing time leads to an impaired yield and difficulties during the continued process. An incorrect temperature leads to disturbances of the process possibly leading to a break down. One requirement is thus that the end point of e.g. the slag blowing stage has to be determined to within better than one minute.
Depending on the composition of the melt the flame present above the converter will look different, and thus it can not easily be determined visually, if, and when, the process is to be interrupted.
Thus there exists a considerably technical problem to be solved within the smeltmetallurgy, at endothermic and exothermic processes, and in that connection particularly within pyrometallurgy but also in plasma smelting and electric arc smelting.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows parts of the spectra emitted for PbO and PbS during slag and copper making stages in a copper converting process.
FIG. 2 shows a plot of PbO/PbS ratio vs. Cu content of white metal in a copper converting process.
FIG. 3 shows the calculated partial pressure exceeding 10.sup.-6 bar during the slag production phase versus the amount of air injected per ton matte and the copper content of the matte in a copper converting process.
FIG. 4 shows calculated composition of the gas phase in the copper making stage versus the amount of air being injected per ton matte during the initial slag blowing stage.
FIG. 5 shows a plot of intensity of SO.sub.2 absorption vs. wavelength in a copper converting process.
FIG. 6 shows an emitted spectrum from a converter flame in a small resolution in the interval 200-700 nm in a copper converting process.
FIG. 7 shows a spectrum of a hot spot in the wave length interval 200-300 nm in a copper converting process.
FIG. 8 shows a plot of sodium lines in absorption and emission in a copper converting process.
FIG. 9 shows the changes in relative intensities of two emissions of one product at various temperatures in an iron/steel production process.
DESCRIPTION OF THE PRESENT INVENTION
It has now surprisingly been shown possible to solve the above mentioned technical problems by means of the present invention which is characterized in that one first determines, for each endothermic and exothermic smeltmetallurgical process and/or process step, characteristic optical emissions or absorptions and identifies the atomic and/or molecular origin of the emissions/absorptions, that one during an ongoing process run registers changes in the characteristics of the emissions/absorptions
REFERENCES:
patent: 3513307 (1970-05-01), Dudgeon
patent: 4008075 (1977-02-01), Petersson
patent: 4345746 (1982-08-01), Schleimer et al.
patent: 4425160 (1984-01-01), Mehta et al.
patent: 4651976 (1987-03-01), Arima et al.
Alden Lars E. M.
Persson Erik W.
Wendt Erik W.
Andrews Melvyn J.
Scandinavian Emission Technology Aktiebolag
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