DETERMINATION OF THE QUANTITY OF SLAG IN METALLURGICAL MULTI-SLAG PROCESSES

摘要

1,216,130. Slag determination in oxygen steelmaking. SALZGITTER HUTTENWERK A.G. April 23, 1968 [April 28, 1967], No.19173/68. Heading C7D. [Also in Division G1] The quantity of slag present at various stages of metallurgical multi-slag process is measured by the use of a radioative tracer. The method can be used during the LDAC multi-slag process in which phosphorus-rich pig iron is refined by blowing pure oxygen mixed with lime dust into the surface of the melt through a water-cooled lance. The tracer used may be Lanthanum 140, Barium 140, or Yttrium 90, having a half life of 61 hours. All of these disperse quantitatively through the slag phase of the melt. The method is described with reference to the first and second melts of such a multi-slag process, each melt comprising first and second blow periods. In the first melt, the approximate quantity of slag in the converter after removal of slag at the end of the first blow period, is known and thus it is known approximately how much will be present at the end of the second blow period. This gives a guide as to how much radioactive isotope to add at the beginning of the second blow period. During this period the isotope disperses thoroughly in the slag and at the end of the period a sample is taken, the radioactivity of a predetermined surface area is detected to obtain a pulse rate measurement. From a calibration curve, the concentration or amount of isotope in the sample is read off and using this and the value of the original isotope concentration added, the weight of slag in the converter is calculated. Thus at the beginning of the second melt the slag quantity is known accurately. In this melt, a known quantity of slag is drawn off at the end of the first blow period and bearing in mind that some isotope is still left in the slag remaining and that some decay of this isotope has occurred a suitable further quantity of isotope is added at the beginning of the second blow period. Sampling is repeated as before at the end of this period.