U.S. patent number 3,883,399 [Application Number 05/262,672] was granted by the patent office on 1975-05-13 for charging coke oven blended coal and an overlay of briquettes.
This patent grant is currently assigned to Sumitomo Metal Industries Limited. Invention is credited to Naomichi Nire.
United States Patent |
3,883,399 |
Nire |
May 13, 1975 |
Charging coke oven blended coal and an overlay of briquettes
Abstract
This specification discloses a carbonization method of coal
briquette which made from non-coking coal and poor coking coal.
According to this method, a formed coke for blast furnace can be
produced economically by using conventional coke oven.
Inventors: |
Nire; Naomichi (Takatsuki,
JA) |
Assignee: |
Sumitomo Metal Industries
Limited (Osaka City, JA)
|
Family
ID: |
12665718 |
Appl.
No.: |
05/262,672 |
Filed: |
June 14, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Jun 17, 1971 [JA] |
|
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46-43510 |
|
Current U.S.
Class: |
201/6; 201/8;
201/40; 201/24 |
Current CPC
Class: |
C10B
57/04 (20130101); C10B 53/08 (20130101) |
Current International
Class: |
C10B
57/00 (20060101); C10B 53/08 (20060101); C10B
57/04 (20060101); C10B 53/00 (20060101); C01b
047/10 (); C10b 057/04 () |
Field of
Search: |
;201/24,23,21,40,6,22,25,20,8.42 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yudkoff; Norman
Assistant Examiner: Edwards; David
Attorney, Agent or Firm: Watson, Cole, Grindle &
Watson
Claims
What is claimed is:
1. A method for carbonizing coal briquettes utilizing a
conventional coking oven comprising:
charging said oven with a sufficient amount of a blended coal to
fill the oven to a level within the range of between 70 and 94
percent of the effective height of the oven, said blended coal
being capable of conversion into blast furnace coke upon
carbonization thereof;
thereafter placing, on top of said blended coal, a sufficient
amount of coal briquettes to fill the remainder of the effective
height of the oven, said briquettes comprising an admixture of a
soft coking coal and a non-coking carbonaceous substance; and
subjecting the contents of the oven to carbonization to thereby
simultaneously produce blast furnace coke and coke briquettes.
Description
This invention relates to a carbonization method of coal briquette
consisting of poor coking coal and non-coking coal, by using a
conventional coking oven.
According to the growth of the iron and steel industry all over the
world, the metallurgical coking coal is getting increasingly
difficult to obtain, and this trend is becoming increasingly
severe. To cope with this trend, the blend of non-coking coal to
the coal blend for metallurgical coke and the production of
metallurgical coke using non-coking coal as the main raw material
instead of the coking coal have been investigated.
As one manner to make the metallurgical coke from non-coking coal,
there is formed coke method. In this method, the non-coking coal is
formed into briquette prior to high temperature carbonization.
However, the high temperature carbonization of the coal briquette
in this method cannot be done with the conventional coke oven, and
a exclusive equipment for the carbonization of the coal briquette
is required. In addition to that, the exclusive equipment which is
presently available, economically inferior to the conventional
coking oven.
In another method, the coal briquette consisting of poor coking
coal and soft coking coal is used as part of coking coal charging
to the conventional cokeoven (as disclosed in Japanese patent
publication No. 16484/1960). In this method, the caking material
content in the coal briquette is set high (with the caking material
index of 66 to 90 percent) to result in fusing of the coal
briquette with the surrounding coking coal, so that no trace of
briquette can be found in the product coke at all. In an example
disclosed in the Japanese patent publication No. 16484/1960, 40
percent coal briquette are charged together with the usual coking
coal into a 1/4-ton experimental coking oven. However, the bulk
density of the charging coal included the coal briquette (with 40
percent) is increased to 0.78 ton per cubic meter compared to 0.72
to 0.74 ton per cubic meter in case of the 100 percent usual coking
coal. Therefore, in the operation of the practical coke oven, the
discharge of the product from the coke oven get into trouble.
In practice, therefore, in the disclosed method, the proportion of
the coal briquette in the charging coal for the conventional coke
oven is 25 to 30 percent at the most, and the poor coking and the
non-coking coal cannot use more than about 20 percent.
In the method according to the invention, it is possible to use the
poor coking and the non-coking coal by 20 percent or more of the
total charge into the conventional coke oven. Also, it is
essentially different from the above method (disclosed in the
Japanese Pat. publication No. 16484/1960) in that a formed coke can
produce with the conventional coke oven.
An object of the invention is to provide a carbonization method, in
which high temperature carbonization of coal briquette and usual
coking coal can be done separately in the same conventional coke
oven without requiring any exclusive coking equipment and without
causing fusion of the briquette one with another or the briquette
with the usual coking coal.
According to the invention, the usual coking coal and the coal
briquette charged into the coke oven may be carbonized at the same
time.
More particularly, in the carbonization method of the coal
briquette according to the invention, the usual coking coal, which
consist of 20 to 60 percent of hard coking coal, 0 to 40 percent of
soft coking coal and 0 to 50 percent of semi-hard coal so that its
coke strength index (15 mm index in accordance with JIS,
K-2151-1962) is 91 or greater, is charged in a range between 70 and
94 percent of the effective height of the conventional coke oven,
and then the coal briquette coal which mainly is consisted of the
poor coking coal and the non-coking coal or non-caking carbonacious
substance such as petroleum coke is charged in a range between 6 to
30 percent of the effective oven height for high temperature coking
to obtain the metallurgical coke.
According to the invention, it is also possible to charge the usual
coking coal from the charging hole of the pusher side on the coke
oven and then charge only the briquette coal from another changing
hole (on the coke guide side).
The following example is made prior to tests using actual coke
oven.
EXAMPLE
This example used a standard experimental coke oven with a charging
capacity of 25 kg. The quality of coals used in this example are as
shown in Table 1 and Table 2 below:
Table 1
__________________________________________________________________________
Name of coal Proportion Quality of blended coal
__________________________________________________________________________
Keystone (hard coking coal) 15 % Total moisture: 7.7 % Inhercent
moisture: 2.0 % Free swelling index: 61/2 Ash: 7.2 % Balmer (hard
coking coal) 20 % Volatile matter: 28.8 % Fixed carbon: 62.0 %
Devis Blend (semi-hard 15 % coking coal) Wollondilly (semi-hard 20
% Total sulfur: 0.51 % coking coal) Akabira (soft coking 30 % Size
distribution coal) (-3 mm): 73.3 %
__________________________________________________________________________
Table 2 ______________________________________ Name of coal
Proportion Quality of blended coal
______________________________________ Poor caking coal 60 %
Inherent moisture: 1.9 % Ash: 7.2 % Petroleum coke 30 % Volatile
matter: 28.9 % (non-caking) Fixed carbon: 62.10% Coal tar pitch 10
% Total sulfur: 0.62% Free swelling index: 1
______________________________________
The blended coal shown in Table 1 is usual for producing blast
furnace coke. The blend for the coal briquette coal shown in Table
2 consists of the poor coking coal (with 3.2 percent inherent
moisture, 11.8 percent ash, 32.3 percent volatile matter, 52.7
percent fixed carbon and free swelling index of 1) and the
petroleum coke having no caking property. The coke produced from
this poor coking coal is inadequate as blast furnace coke since the
coke strength index is very low, being 30.9; (the 15 mm index
according to JIS is 30.9 and the stability factor according to ASTM
D 294-64 is 7.5).
The raw materials for coal briquette mixed according to the
proportion of Table 2 was pulverized less than 3 mm., and fed on to
a kneader. The coal tar pitch in the mixture is method by the heat
of hot steam blown into the kneader and the mixture is kneaded
sufficiently, and then the mixture was supplied to the briquetting
machine, which is a double roll type and has a briquette pressure
of about 950 kg/cm (line pressure).
The coal briquette produced in the aforementioned way has
dimensions of 28 mm .times. 19 mm and a weight of 10.1 grs. For the
carbonization by the experimental coke oven, 184 kg of the blended
coal shown in Table 1 was first charged uniformly within the
carbonization chamber of the experimental coke oven and then 45 kg
of the coal briquette produced under the above conditions charged
on the blended coal. Then, the charge was carbonized with a flue
temperature of 1,160.degree.C and a coking time of 15 hours and 46
minutes. After carbonization, the hot coke was discharged out of
the oven by a pusher and quenched with water.
In the above manner, it was not recognized that the formed coke
fused with the coke made from the usual blended coal. Table 3 below
shows various properties of these cokes. Both cokes can be used as
blast furnace coke.
Table 3 ______________________________________ Composition and
properties of cokes Proximate Analysis Conventional Formed coke
coke ______________________________________ Ash (%) 10.0 9.8
Volatile matter (%) 0.9 0.8 Fixed carbon (%) 89.1 89.4 Total sulfur
(%) 0.48 0.56 Coke strength 15 mm index by JIS 92.2 94.6 25 mm
index by JIS 86.7 -- 50 mm index by JIS 27.8 -- Stability factor by
ASTM* 53.4 64.4 Hardness factor by ASTM* 62.2 71.6 Average size of
coke (mm) 89.0 27 .times. 27 .times. 18 Porosity (%) 50.5 38.5
Crushing Strength (kg/cm.sup.2) 212 319
______________________________________ *The ASTM stability and
hardness factors were measured according to ASTM 294-1964.
In the coke oven usually used in the iron making industry, the
coking coal is charged into the oven from a charging hole at the
top of the carbonization chamber, and after the carbonization it is
mechanically pushed out of the oven in the horizontal direction.
Also, the coking coal charged into the coke oven should have good
caking property and should be carbonized in the form of masses.
If coal briquette chiefly consisting of poor coking coal and
non-caking material like that shown in FIG. 2, is solely charged
into the coking oven, at the time of pushing the coke out of the
oven the forward component of force exerted to the coke (formed
coke) from the pusher is reduced, so that the pushing eventually
becomes impossible.
FIG. 4 lists of a galvanometer of pusher in pushing tests carried
out by using a industrial coke oven with an oven height of 4 m,
which the efective dimension of carbonization chamber is 3.67 m in
height, 13.68 m in length and 0.70 m in width, and effective inner
volume of 19.2 m.sup.3 (charging capacity of 13.4 tons per oven).
The usual blended coal and the coal briquette according to the
invention charged into the oven chamber, and then the charged
material carbonized at a flue temperature of 1,245.degree.C for a
coking time of 14 hours and 06 minutes.
Table 4 ______________________________________ Kind of charged coal
Electric current at pusher ______________________________________
Usual blended coal 70 to 72 amperes 90 percent usual blended coal
and 73 to 74 amperes 10 percent coal briquette 70 percent usual
blended coal and 75 to 77 amperes 30 percent coal briquette
______________________________________
As is apparent from Table 4, the electric current at the pushe is
lowest in case of the sole usual blended coal. The electric current
is slightly increased in case of 90 percent, that is, 12 tons of
the usual blended coal and 10 percent, that is, 1.4 tons of the
coal briquette. In this case, however, the pushing operation itself
was found to be the same as in the above case. In case of 30
percent, that is, 4 tons of the coal briquette the electric current
at the pusher is further increased. In this case, due to increased
resistance of the coke within the oven the pusher stopped several
times during the pushing operation, but the discharging of the coke
was possible.
However, in tests conducted by charging 30 percent or more of the
coal briquette the number of stoppage of the pusher was increased,
and the discharging of the coke was difficult. Accordingly,
according to the invention the proportion of the coal briquette to
be charged is restricted to be 30 percent or less. According to the
invention, the lower limit of the proportion of the coal briquette
to be charged is made to be 6 percent, because with less than 6
percent of the proportion of the poor coking coal wide reduction of
the coke cost cannot be expected.
As has been described in the foregoing, according to the invention
the usual coking coal is charged in a range between 70 and 94
percent of the effective height of the coke oven while the coal
briquette is charged in a range between 6 and 30 percent of the
effective oven height on the usual coking coal for separately
carbonizing the usual coking coal and coal briquette in the same
coke oven by the usual high temperature carbonization method. Thus,
it is possible to economically and inexpensively produce formed
coke for blast furnace from poor coking coal with the conventional
coke oven, and save the hard coking coal.
The coal briquette on the usual coking coal either slightly fuses
or does not fuses at all depending upon the bituminous substance
content (with less bituminous substance content the fusion being
weaker). Therefore, when the oven lid is removed at the time of
pushing out the coke it is possible that coal briquette in contact
with the oven lid drops, which is very hazandous. To prevent this,
it is better to use an oven lid slanted toward the oven
chamber.
* * * * *