On the Basic Bessemer Process
by Pierre Coheur and Hans Kosmider
DISCUSSION, H. B. Emerick and W. O. Phitbrook,
Chairmen
A. B. Wilder (National Tube Div., United States Steel
Corp., Pittsburgh)-Drs. Coheur and Kosmider are well
qualified to dISCUSS the basic-bessemer process and
therefore have presented a very interesting paper.
There are several questions which may develop information of further interest:
I-In blowing with oxygen/steam, does the presence
of hydrogen gas affect the properties of the finished
steel with respect to embrittlement or flaking tendencies?
2-Is it practical to use air during the first half of the
blow and oxygen/steam during the second half and
produce steel with 0.004 pct N? This would reduce the
cost of oxygen.
3-Can steel be produced from iron containing 0.25
pct P rather than 1.75 pct P with oxygen/steam?
4--To what extent does the use of steam cool the
bath?
5-What effect does oxygen/steam blowing have on
tuyere life?
6-Table III shows that 1755 cu ft of oxygen are required per ton of steel. This value appears to be low,
and a question is raised regarding the conversion of
metric into English units.
7-May oxygen with 50 or 75 pct purity be used for
oxygen/steam blowing to produce steel with 0.004 pct
N?
8-In Figs. 17 through 19 concerning work hardening, were the steels heat treated and what was the
nitrogen content of the open hearth steel?
Pierre Coheur and Bans Kosmider (authors' reply)First, as we reported, we are using the oxygen/steam
mixtures in order to decrease the nitrogen content of
our rimmed steel. In this case, we have never noticed
any embrittlement or flaking tendency of the finished
steel. Moreover, we have checked the H. content of the
liquid steel at the casting pit. The time lapse from the
moment the sample was taken from the ladle to the
moment we placed it in the dry ice was 30 sec.
Our latest figures are: 0.24 to 0.37 cu in. (4 to 6 cu
cm) of H. per 3.5 oz (100 g) when blowing with
oxygen/steam vs 0.24 to 0.31 cu in. (4 to 5 cu em) when
blowing with enriched air.
2---Blowing in two phases certainly reduces the cost
of oxygen, but from a theoretical point of view it is
not recommended, since the two kinds of blast passing
through the bottom do not have the same volume. In
order to smooth the blow, it is always advisable to
adapt the blowing surface of the bottom to the composition of the blast. Nevertheless, we have blown many
charges in two phases and produced a steel with an N.
content below 0.004 pct. The oxygen consumption was
of the order of 1412.40 cu ft (40 cu meter) per ton of
iron, Le., 30 pct less than when blowing with
oxygen/steam only.
3-The answer is yes.
I should like to mention the results obtained by E.
Eichkoltz, Behrendt, and Th. Kootz.' In the course of
one week, blowing with atmospheric air, they converted in a basic converter more than 6613.8 short tons
(6000 metric tons) of pig iron containing 2.5 to :U pet
Mn, 0.50 to 0.85 pct SI, 0.10 to 0.25 pct P, and 0.02 to
0.04 pct S. The temperature of the pig iron, when
charged, was between 1240° and 1260°C, except for a
specIal lot in which the temperature ranged from 11900
to 1200°C. The total blowing time was practically the
same as that for the standard practice and was related
to the composition of the pig iron. However, the time
consumed before pouring the steel was shorter because
of smaller quantities of slag and the lighter addition of
Fe-Mn. A great number of blows might be poured in
the ladle without adding Fe-Mn. The loss of Fe is more
than 1 pct below that of the basic-bessemer blows, but
the yield is about the same. Lining wear was about 10
pet higher, while bottom life was improved.
Dr. Kosmider recently had the opportunity of successfully blowing numerous charges of steel, containing traces of iron ("Stahl Eisen"), the composition of
which was: 4.2 pct C, 2.1 pct Mn, 0.50 pct P, and 0.65
pct SL He used either an enriched air or the mixture of
oxygen/steam. His results were recently discussed in
Diisseldorf and will be published shortly"
4--A mixture of oxygen/steam containing between
60 and 65 wt pct oxygen and 40 to 35 wt pct steam has
the same thermogenic power as atmospheric air for a 15
ton converter. In other words, for a given liquid iron
and when other circumstances are equal, we add the
same quantity of scrap to cool the bath when blowing
with either atmospheric air or with oxygen/steam. If
we want to increase (or decrease) the quantity of the
metallic addition, we have to increase (or decrease)
the oxygen content of the blast. For example, with 56
pct of oxygen in the mixture, the quantity of scrap
added into the converter is 3 to 4 pet of the iron. With
63 pct of oxygen in the mixture, the amount of scrap is
6 to 9 pct.
5---When the steam condenses on the refractories,
the life of the tuyeres is indeed very short. That is one
of the reasons why we superheat the steam or the
oxygen/steam mixture. By doing so, the bottom life is
almost the same as when blowing with atmospheric
air.
6--A figure of 63 cu meters of oxygen per metric ton
of iron, or 2000 cu ft per short ton of iron, is correct
when blowing with oxygen/steam.
7-The purity of the oxygen we used is between 95
and 99 pct. We have had no experience with blows of
50 or 75 pct pure oxygen.
8-The nitrogen content of the open hearth steel was
between 0.004 and 0.006 pet. In Figs. 18 and 19, the
steels were not heat treated. The steels in Fig. 17 were
normalized.
Details of our physical results can be found in refs.
3 through 5.
1 E. Elchkoltz, G. Behrendt, and Th. Kootz: Stahl u ..d Bl.....
(1940) 80, pp. 61-72.
• H. Kosmlder: To be published In Stahl u ..d Else...
• Revue de Moltallurgte (1951) pp. 17-46.
• Revue U..lverselle des MI..es (April, November 195:1).
• Ouature Ml!t411ique (April 11154).
Solid Phase Indentification in Partially Reduced Iron Ore
by Gust Bitsianes and T. L. Joseph
DISCUSSION, Gerhard Derge and John F. Elliott,
Chairmen
R. Wild (Imperial College of Science & Technology,
TRANSACTIONS AIME
London, England)-Messrs. Bitsianes and Joseph have
made a most interesting and valuable contribution to
our knowledge of the behavior of iron ores during
NOVEMBER 1954, JOURNAL OF METALS-130S