Process and Apparatus for Calcining Lime-stone and other Substances, and Recovering Valuable By-products.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Process and Apparatus for Calcining Lime-stone and other
Substances, and Recovering Valuable By-products.
PAUL NAEF, Ph.D., Chemical Engineer, 15, 3rd Avenue, New Brighton, S.T.,
New York, U.S.A., do hereby declare the nature of this invention to be as
follows:-
-
This invention relates to a process and apparatus for calcining limestone and
similar substances.
The process is specially intended to be carried on in connection with the smelt-
ing of ores, for the calcination of the limestone required as flux in the blast
furnace; but can also be used for other purposes.
Objects of the invention are, to recover the cyanides formed in the blast fur-
nace; to economise fuel by calcining the limestone in a separate apparatus; to
make the production of iron; the recovery of by-products the coking of coal; the
calcining of the limestone, as well as the handling of all materials, automatic
operations. The process is intended to be carried on in connection with my
coking process, for which application for Letters Patent was made by me 7951/98,
dated under International Convention Sept. 7, 1897.
It is an established fact that large amounts of cyanide are formed in the lower
part of iron blast furnaces. This cyanide is mostly destroyed in the upper part
of the furnace by the oxydising action of oxide of iron, and only a small amount
is found in the gases leaving at the top.
An important feature of my invention consists in taking off incandescent gases
from blast furnaces, before the destruction of much cyanide has taken place.
These incandescent gases I utilize for the calcination of limestone, for the produc-
tion of coke and by-products & also for the reduction of ore in some cases.
In the drawings-Fig. 1, shows a vertical section through the apparatus:-
No. 1 is a blast furnace which may be of any ordinary construction. No. 2 is
the coking apparatus. No. 3 the apparatus for calcining the limestone.
Incandescent gases are taken off from the blast furnace through ducts 4, which
lead into a main channel 5, encircling the furnace. This channel has openings
for blowing out dust when necessary. It is connected to the coking apparatus 2
FD 871

page_text: and calcining apparatus 3 by pipe 7.
Water cooled dampers 8 and 9 are
arranged to shut off incandescent gas from the calcining and coking apparatus if
necessary.
The coking apparatus consists of a shaft 10, and is here shown with a conical
bottom 11 and doors 12 for withdrawing the coke. It is charged by conveyor 13.
The incandescent gas enters through ducts 14. The gas containing ammonia and
tar leaves through pipe 15.
The coke is discharged into a storage hopper 16, which is connected at the
bottom to a conveyor 17, which delivers the coke into hopper 18. Steam is intro-
duced through pipes 17" and water through pipes 17b.
The lime kiln 3 consists of a shaft 19, supported on iron pillars 20. It is
charged from hopper 21, by conveyor 22. Incandescent gas is introduced through
the annular channel 23, and ducts 24, which are arranged at such a height, that
the resistance offered to the gas upwards and downwards is about the same.
The burnt lime is withdrawn from the conical bottom 23" by opening doors 24",
into the storage hopper 25. From this hopper it is fed into hopper 18 by con-
veyor 26. The iron ore is fed into the same hopper 18, from hopper 27, by con-
veyor 28, and the suitable smelting mixture of lime, iron ore and coke is obtained
by regulating the speed of the conveyors 17, 26, 28. This smelting mixture is
elevated into hopper 29, on the top of the blast furnace by elevator 30, which
discharges into conveyor 31.
By this arrangement, the entire operations of making the smelting charge,
elevating the same and charging it into the blast furnace, is performed entirely
automatically. Hopper 27 is so arranged that iron ore can be dumped into it
from railway cars.
The cyanide contained in the incandescent gases taken from the blast furnace,
can be decomposed to ammonia by injecting steam into the calcining apparatus.
For recovering the ammonia or ammonium-bicarbonate, the gases from the kiln
are passed through any suitable washing apparatus-not shown. If cyanide is to
be recovered as such-the gases are treated by any of the methods which have
been found suitable in gas works, for the absorption of cyanides from gases.
It is apparent, that this calcining process can be carried out by means of the
incandescent gases from other than blast furnaces, and without recovering
ammonia or cyanide.
The gas leaving the calcining apparatus can (preferably after washing) be
mixed with the gases entering the coking apparatus, or they can be mixed with
air or gases passing through highly heated fuel, for the purpose of reducing the
carbonic acid to carbonic oxide.
The process is not limited to the calcination of limestone alone, but is applicable
for other substances, for instance the burning of cement.
Having now described my invention what I claim as new, is :-
1. The method of recovering cyanide from hot gases containing the same,
which consists in passing these gases through limestone or other materials of a
similar nature, and afterwards revolving cyanide and ammonia from the resulting
gases.
2. The method of producing cyanide, which consists in taking off hot gases from
blast furnaces, utilizing the same for calcining limestone or other material, and
treating the resulting gases for recovery of cyanide.
3. The method of recovering ammonia from hot gases containing cyanides,
which consists in passing said gases through limestone or other material in presence
of steam, and treating the resulting gases for recovery of ammonia.
4. The method of calcining limestone and other materials, which consists in
passing hot combustible gases through the same.
5. The method of calcining limestone and other materials, which consists in
taking off hot gases from a blast furnace, and conducting the same through the
limestone or other materials.

page_text: 6. The combination of a blast furnace having arrangements for taking off gases
some distance above the buyeres, with an apparatus for calcination of limestone
or other materials, by said incandescent gases.
7. An apparatus for calcining limestone or other material, consisting of a fur-
nace shaft, having an annular channel encircling it and ducts into the furnace
arranged at such a height, that burnt lime or other material can be withdrawn
without escape of gas.
8. The combination of the coking apparatus, the calcining apparatus, and the
means of producing a smelting mixture of ore, coke and lime, consisting of hop-
pers and conveyors for each material.
9. The combination of a blast furnace with a coking apparatus, an apparatus
for calcining limestone means for producing a smelting mixture, means for raising
the mixture into a hopper on the top of the blast furnace and means for continu-
ously feeding it into the furnace.
10. The combination with a calcining apparatus of a storage hopper on a lower
level from which the calcined material can be discharged in regulated quantities.
11. A calcining apparatus consisting of a furnace shaft, having means for feed-
ing limestone into said shaft on top, and a funnel bottom with sliding doors, for
withdrawing the calcined material at the bottom.
DJ 11 15IL
1 1000
PAUL NAEF,
Applicant.
Process and Apparatus for Calcining Lime-stone and other
Substances and Recovering Valuable By-products.
PAUL NAEF, Ph.D., 15, 3rd Avenue, New Brighton, S.T., New York, U.S.A.,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the follow-
ing statement:-
This invention relates to a process and apparatus for calcining limestone and
similar substances.
The process is specially intended for the calcination of limestone required in
the smelting of ores, but can also be used for the calcination of other materials.
Objects of the invention are:-to recover the cyanides formed in blast or other
furnaces; to economize fuel by calcining the limestone, which is required for
smelting the ore in a separate apparatus; to make the production of iron, the
recovery of byproducts, the coking of coal, the calcining of limestone, as well as
the handling of all materials automatic operations.
The process
is intended to be carried out in connection with my coking process,
for which applications for Letters Patent have been made by me, 7951, 7952 and
7953 2nd April /98; date under International Convention 7 Sept /97.
Large amounts of cyanide are formed in the lower part of iron blast furnaces.
This cyanide is mostly destroyed in the upper part of the furnace by the oxydi-
sing action of oxide of iron, and only a small amount is found in the gases leaving
at the top.
An important feature of my invention consists in taking hot gases from blast
furnaces, before the destruction of much cyanide has taken place. These gases I
utilize for the calcination of limestone; for the production of coke and its by-
products; and also for the reduction of ore, in some cases. Any cyanide, con-
tained in the hot gases is recovered in the calcining as well as in the coking process.

page_text: The coking process furnishes further, the ammonia set free from the fuel by the
distillation, and still further a considerable amount of ammonia produced by the
action of steam on the nitrogenous compounds of the coke.
Reference is made to Application No. 9462 and 9463, of even date /98.
The metallurgical features of the process are described in Application 9463, /98.
The recovery of cyanide or ammonia from hot gases in connection with the
coking process is described in Application 9462, /98.
In the drawings, which have been left with my Provisional Specification, Fig. 1
shows a vertical section through the apparatus.
Referring to Fig. 1 No. 1 is a blast furnace of ordinary construction; No. 2,
is the coking apparatus, No. 3 is the apparatus for calcining the limestone. In-
candescent gases are taken off from the blast furnace through ducts 4, which
lead into a main channel 5 encircling the furnace. This channel has openings G
for blowing out dust, when necessary; it is connected to the coking apparatus 2,
and calcining apparatus 3 by pipe 7. Water cooled dampers 8 and 9 are
arranged to shut off the incandescent gases from the coking and calcining appar-
atus if desired.
The coking apparatus consists of a shaft 10, and is shown here with a conical
bottom 11, and doors 12, through which the coke is discharged. It is charged
by conveyor 13, with coking material from the hopper above it. The incandescent
gases enter through the ducts 14. The gases containing ammonia and tar leave
through pipe 15. The coke is discharged into a storage hopper 16, which is con-
nected at the bottom to a conveyor 17, which delivers the coke into hopper 18.
The calcining apparatus 3, consists of a shaft 19, supported on iron pillars 20.
On the top it has a mechanical charging arrangement consisting of a hopper 21,
and a conveyor 22. The calcined material is withdrawn from the conical
bottom 23. For this purpose sliding doors 24", worked by cog-wheels are arranged
in the conical bottom, through which the burnt material is discharged into storage
hoppers 25. If desirable, rollers can be arranged in the conical bottom as shown
at 12 in the coking apparatus.
The calcining apparatus is connected with the blast furnace by means of pipe 7.
The pipe joins at one end with the annular channel 5, of the blast furnace, which
receives the hot gases through the ducts 4. At the other end it is connected with
the annular channel 23 of the calcining apparatus. This channel which is pre-
ferably lined with fire brick encircles the calcining apparatus and is in connection
with the inside of the shaft 3 by means of radial ducts 24. The gases leave the
calcining apparatus on top through pipe 15° and are conducted to any suitable
washing apparatus,-not shown.
In pipe 7, which leads from the blast furnace, is arranged a valve 9 for shut-
ting off the gases, for the purpose of stopping the calcining furnace without inter-
fering with the blast furnace.
The operation of the calcining apparatus is as follows:-The material, which
has to be calcined is charged by mechanical or other means into hopper 21. The
conveyor 22 discharges the same in regulated quantities into the furnace. As
the material gradually descends in the apparatus it meets the hot gases from the
blast furnace. These gases leave the blast furnace through the tuyeres 4 and then
pass on through the annular channel 5, surrounding the same, into the pipe 7
through which they are conducted into the annular channel 23 and through the
ducts 24 into the calcining apparatus. The material gradually reaches a tem-
perature at which carbonic acid is driven off and is completely calcined by the
time it has descended as far as the ducts 24.
It is an important feature of the calcining apparatus to have the inlets 24 for
the hot gases arranged at such a height, that the resistance to the passage of the
gases in the downward direction is the same or higher than that of the upward
direction. This arrangement enables the withdrawal of the calcined material at
the bottom without loss of gas.
From the hopper 25 the lime is fed into hopper 18 by convevor 26. The iron

page_text: ore is fed into the same hopper 18 from the hopper 27 by conveyor 28 and the
suitable smelting mixture of lime, iron ore and coke is obtained by regulating
the speed of the conveyors 17, 26 and 28. This smelting mixture is elevated into
hopper 29 on the top of the blast furnace by elevator 30, which discharges into
conveyor 31.
By this arrangement the entire operations of making the smelting charge, eleva-
ting the same and charging it into the blast furnace, is performed entirely
automatically.
Hopper 27, is so arranged that the iron ore can be dumped into it from railway
cars.
The cyanide, in the hot blast furnace gases passes partly upwards in the cal-
cining apparatus 3 with the gases, and it is partly condensed and carried down-
wards by the lime. By introducing a small amount of steam into the calcining
apparatus, in the same way as is shown in the coking apparatus 2, at 17 and 17b;
the cyanide is converted into ammonia according to the equation;-
2NaCN + 3H₂O
=
Na₂+ 200 + 2NH₂.
-
This ammonia is recovered by passing the gases from the calcining apparatus
through a suitable washing apparatus not shown in the drawings.
If cyanide is to be recovered as such, it is advisable to introduce only a small
amount of steam into the lower part of the apparatus, sufficient to convert the
cyanide carried into the lower part by the lime, into ammonia. The cyanide
carried upwards, in the form of vapour, by the gases will then leave the apparatus
as such, which can be recovered by conducting the gases through a washing plant
containing an absorbent for cyanide.
It is apparent, that this calcining process can be carried out by means of incan-
descent gases from other than blast furnaces, and without recovering ammonia
or cyanide.
The gases leaving the calcining apparatus can--preferably after washing-be
mixed with the gases entering the coking apparatus, or they can be mixed with
air or gases passing through highly heated fuel, for the purpose of reducing the
carbonic acid to carbonic oxide.
The process is not limited to the calcination of limestone alone, but is appli-
cable for other substances, for instance, the burning of cement.
The general construction of the apparatus may be varied as the case may re
quire to effect the best results of the process, without departing from the spirit
of the invention.
For the purpose of increasing the production of cyanide, an alkali may be mixed
with the coking material in the coking apparatus 2 as described in my Applica-
tion 7953/98.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The method of recovering cyanide from hot gases containing the same,
which consists in passing these gases through limestone or other materials of a
similar nature, and treating the resulting solid and gaseous products for the
recovery of cyanide and ammonia.
2. The method of producing cyanide, which consists in taking hot gases from
blast furnaces at a height where little cyanide is destroyed, utilizing the same for
calcining limestone or other materials of a similar nature, and treating the
resulting solid and gaseous products for the recovery of cyanides.
3. The method of recovering ammonia from hot gases containing cyanides,
which consists in passing these hot gases through limestone or other materials
of a similar nature in the presence of steam, and treating the resulting gases for
the recovery of ammopia.
4. The method of calcining limestone and other materials, which consists in

page_text: taking hot gases from a blast furnace and conducting the same through the lime-
stone or other materials of a similar nature.
5. The method of calcining limestone and other materials of a similar nature,
which consists in passing incandescent or highly treated combustible gases through
the same.
6. The method of producing cyanide or ammonia from atmospheric nitrogen,
which consists in smelting iron in a blast furnace in the presence of an alkali,
taking hot gas from the blast furnace at a height where little cyanide is destroyed
conducting said gas through limestone or similar substances for the purpose of
calcining the same, and treating the resultant gaseous and solid products for the
recovery of cyanide or ammonia.
7. The combination of a blast furnace having arrangements for taking off
gases some distance above the tuyeres with an apparatus for the calcination of
limestone or other materials by the said gases.
8. An apparatus for calcining substances by means of hot combustible gas,
consisting of a shaft having the lowest inlets for gaseous fluids at such a height,
that the resistance upwards and downwards, through the substance, is about the
same, so that the burnt substance can be withdrawn without loss of gas.
9. An apparatus for calcining limestone or other material, consisting of a fur-
nace shaft having an annular channel encircling it, and ducts into the furnace
arranged at such a height, that burnt lime or other material can be withdrawn
without loss of gas.
10. The combination of the coking apparatus, the calcining apparatus, and the
means of producing a smelting mixture of ore, coke and lime, consisting of hop-
pers and conveyors for each material.
New York dated Lik* do
ST1000
PAUL NAEF,
Applicant.