Pittsburg dispatch. [volume] (Pittsburg [Pa.]) 1880-1923, 1890-10-11
THE DARBY PROCESS.

| HI DARBY PRUCtSS,
Chairman Thielen, of the Phoenix Works,
Gives the Results of the wen-Known
Managers ExperiInents-How Recarburk
sation is Done by the Method.
DR.. Howe, of Boston, was called to the
chair while President A. Thielen read his
paper "On the Darby Process of Recarburi-
sation." Mr.. Thielen is managing director
of the Phoenix Steel Works at Ruhrort,
Rhenish Prussia, and one of the best prac-
tical students of metallurgy in the world.
His paper was as follows:
AS is widely known, in order to produce in
the converter, by means of Sir Henry Besse-
mer's great invention, steel of 4 wished-for per-
centage of carbon two methods present them
selves. By the one the process is stopped when
the bath possesses the desired contents of car
bon; by the other the bath is completely decar-
burised, and then the wished for carbon added
in the form of spiegel. ferro-manganese, ETC.
In Germany the latter method only came into
use and was retained when the Thomas-Gil-
christ process for the production of steel, low
in phosphorus, from highly phosphoric iron in
the basic converter came successfully into use
DECARBURIsATIoN IS NECESSARY.
The more so as from tho nature of the proc
ess, before dephosphorisaton takes place.
complete decarburlsation is necessary. But
while, by tine old acid process the carburIsation
readily takes place by the simple addition of
spiegeeisen etc, the new process brought with
it difficulties, not easy to overcome inasmuch
as the oxides which are always present in the
basic process TO a larger or smaller extent, and
alSothe phosphoric acid of the Stag takes part in
the reaction. Even il one succeeded in remov-
ing part of the oxide by pouring off the Stag
and regulating the amount left dissolved in the
bath by SO perfecting the process, that there
would be approximately an equal amount re-
naming in each charge. and even if the danger
OF rephosphorisation were diminished by as CON-
plete removal of the Stag as possible and by
suitable Stag additions made to the still
remaining Stag, still the:production of low phos-
phorus steel high in carbon could not be ac-
complished SO readily as not to make the in
PRODUCTION of another simple method of car
bursing well worth wishing for. The circum-
stances are similar as regards the basic and
acid open hearth processes.
1t can be readily understood, therefore, why,
after the Introduction of the method of making
steel In basic-lined vessels, proposals which
have been formerly made for the introduction
OF carbon other than by the indirect way, by
means of spiegel, ETC., but which had hitherto
remained without results should be brought
forward again from various quarters. All of
these processes were based on the known fact
of the great affinity between carbon and iron at
high heats. 1t was sought to reduce and car
buriZe the bath of steel by the introduction of
carburetted gases, by the addition of tar, Pc
substances with solid bodies. such as burnt
dolomite. However, the results of all these
experiments did not lead to the permanent In
PRODUCTION of any Of them IN practical work,
until Mr.. John Henry Darby the Managing
director of the Brymbo Steel Works, sue
ceeded in finding solution of the problem
Having attentlvely remarked an increase of
carbon which took place in two pieces which
had been treated in the coal fire for welding
he brought fluid steel into intimate contact with
solid carbon, the result being rapid absorp-
ton of the carbon by the steel Supported by
this experiment he founded on it his patented
process by which fluid steel can be carburised
by filtration through pieces of carbon, prefer
ably in the form of graphite or wood charcoal
etc. This consists of a sheet-iron cylinder
open at the top and closed at the bottom by
plate pierced with numerous holes. the whole
being lined with refractory material 1t is
filled with the carbonaceous material and in
serted either between two steel ladies or be-
tween the SiemenS furnace and the steel ladle
The fluid steel takes its way through the inter
stices of the pieces of carbon, and is thereby
brought by absorption of the carbon, to the
wished for percentage of carbon.
HOW DARBY EXPER1dENTED.
MIR. Darbys experiments extended wholly to
the carburisng OF open-hearth steel. and he
succeeded by his process in conjunction with
the basic process in producing from phosphoric
raw material very excellent product which
with any wished for percentage Of carbon to
small traces of other bodies. and consequently
is distinguished from all hitherto known OPEN
hearth steel by its exceeding toughness. 1t
has been worked up into chisels, knives wire.
etc., with the best results. And there was a
very great certainty in obtaining the right per-
centage of carbon. the percentage obtained
varying from that wished for seldom more
than DOL per cent to 0.02 Der cent The rolling
quality of the material, although only very
small additions of ferro-manganese or ferro-
silicon were made. was very. good. The
process was very soon exclusively EN-
ployed at Brymbo. for the harder steels, but in
order to introduce his system to the Bessemer
process, Mr.. Darby entered into an agreement
with the Phoenix Company of Laar near Rub
rort on the Rhine. The experiments were ar
ranged in the Basic Bessemer works. The car
bursing vessel was arranged between two
ladies standing one over the other and the
steel carburised while streaming from the first
into the second ladle by the stream of carbon
aceous material issuing, regulated by the valve
handle. 1t quickly appeared, however that
the basic Bessemcr steel, although readily car
bursed, yet thereby lost its rolling qualities to
such an extent that the ingots fell to pieces in
the rolls. On inquiring into the cause of this it
was discovered to be due to the method of
carrying out the process, viz: that for four
minutes, more than 60 fine streams of steel
were oxidized, by means of the atmospheric
oxygen. 1t was sought to overcome this draw
back by replacing the so holes in the bottom of
the vessel by one of suitable diameter. A con-
siderable Improvement In the rolling quality of
the ingots was thereby produced. But the
rolling quality attained was not equal to that
of the ordinary Thomas ingots.
SOME PRETTY LARGE INGoTs.
The carburising vessel was replaced by a
refractory lined funnel. open at the bottom,
which was arranged between the casting ladle
and the molds. By an arrangement attached to
the side of the casting crane it was possible to
introduce into the funnel the ground carbon
aceous material little by little in q well regu-
lated stream. This arrangement consists of
an accurately bored cylinder, provided with
lathe-cut worm. As is readily apparent the
amount of carbonaceous material forced out,
is proportional to the number of rotations
which the endless screw makes, which can be
accurately regulated. By the employment Of
this apparatus the carburising is safely done in
the wished for manner and good rolling ingots
obtained. The ground coke appeared to be
more quickly absorbed than the graphite, SO
that the whole of the experiments were carried
out with this material. 1t was found that with
lngots weighing lao kilos and measuring l6
inches square the carbon was very equally dis
tributed throughout. By some attention the
frequently occurring increase of carbon In the
top parts of ingots of this weight was success
fully overcome by q lessened addition of carbon
in the upper part In order to test the equal
distribution Of the carbon, ingos were rolled |