Note: Descriptions are shown in the official language in which they were submitted.
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NOVEL COMBINED GRAPHITIZED IRREGULAR CATHODE FOR
ALUMINUM AND GRAPHITIZED CATHODE STOP BLOCK THEREOF
FIELD OF THE INVENTION
[00011 The invention belongs to the technical field of aluminum electrolysis,
and more
particularly relates to an aluminum electrolysis irregular cathode for
preparing metal
aluminum by fused salt electrolysis process and a graphitized cathode stop
block thereof.
BACKGROUND OF THE INVENTION
[00021 Aluminum is prepared by alumina fused salt electrolysis process with
the
fundamental principal that: electrochemical reaction of molten A12O3 occurs
under the
action of direct currents between anode and cathode to separate Al/O, Al3+
acquires
electrons constantly at cathode to form Al drops which are accumulated to
create a large
amount of aluminum electrolyte, while 02 loses electrons constantly at anode
and is
reacted with C to generate a large amount of C02, the chemical equation is
expressed as
2A1203+3C=4A1+3CO2, and considerable electric energy is required during this
reaction.
Direct current consumption of aluminum electrolysis is determined according to
the
following formula: direct current consumption = 2980xV/.t (V represents cell
voltage that
changes along with the change of electrode distance, and represents current
effect, the
current electrolytic cell has the current effect ranging from 0.93 to 0.95).
Practice has
proved that: the distance (electrode distance for short) between the anode and
the level of
the aluminum electrolyte has a tremendous influence on the current consumption
for
electrolytic aluminum, and in case that the current common planar cathode is
used, the
direct current consumption for the production of metal aluminum by fused salt
electrolysis
process ranges from 13500 to 13800kWh/tAl. As aluminum electrolytic cell is
influenced
by charging, magnetic field, electric field, anode replacement, anode gaseous
escape and
other factors, fluctuation of the level of the aluminum electrolyte inside the
cell could
occur to form `turbulence', which, on one hand, can `stir' electrolyte to
further reduce
precipitation of electrolytes and favor production, on the other hand, leads
to fluctuation of
the liquid level so as to result in the increase of the `electrode distance',
thereby raising
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current consumption, meanwhile, the `turbulence' is liable to cause abrasion
to cathode to
shorten the service life thereof.
[00031 In the aspect of the study and the invention of irregular cathode for
aluminum,
to reduce current consumption of aluminum electrolysis, traditional method is
characterized in that stop block is prepared from the same raw materials as
body block and
usually integrated with body block, therefore, the service life and other
properties of such
an aluminum electrolysis cathode are dramatically limited, just as the
overseas and
domestic publication documents we have searched:
[00041 1. China Patent, Name: Aluminum Electrolytic Cell with Irregular
Cathode
Carbon Block Structure, Application (Patent) Number: 200710010523.4,
Application Date:
2007.3.2, Classification Number: C25C3/08(2006.1) Applicant (Patent Right):
FENG,
Naiyang, Abstract: The aluminum electrolytic cell with irregular cathode
carbon block
structure comprises a groove casing, a refractory heat-preserving material
arranged at the
bottom, an anode and a cathode, a plurality of raised structures are formed on
the surface
of a structurally irregular cathode carbon block, the aluminum electrolytic
cell with
cathode structure according to the invention can lessen flow rate of cathode
aluminum
electrolyte in the electrolytic cell and reduce fluctuation height of the
aluminum
electrolyte, in order to enhance the steadiness of the level of the metal
aluminum
electrolyte in the aluminum electrolytic cell, lower loss caused by aluminum
dissolution,
raise current efficiency, shorten electrode distance and reduce electric
energy consumption
for aluminum electrolysis, and mixture or precipitate of thick cryolite melt
alumina can be
formed between raised walls at the bottom of the cathode in order to prevent
the cathode
aluminum electrolyte from flowing to the bottom of the electrolytic cell
through cracks and
gaps at the bottom of the electrolytic cell to melt steel bar, thereby
achieving the purpose
of prolonging the service life of the electrolytic cell. A raised irregular
cathode carbon
block of the invention is integrated with body block by means of connection
and is made of
the same material as the cathode carbon block of traditional electrolytic
cells, and the
irregular cathode carbon block can be made of anthracite, or made of
artificial graphite
scrap or mixed material of anthracite and artificial graphite scrap, or be
graphitized or
semi- graphitized.
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[00051 According to the invention, improvement for the cathode structure of
aluminum electrolysis is achieved to facilitate production and operation and
obtain
beneficial effect to a certain extent; however, the following defects are
still present:
[00061 a) The raised part is made of the same material as the body and has the
service
life shorter than the body owing to large washout of the `turbulence' of the
aluminum
electrolyte, hence, the power saving effect decreases dramatically as the
raised part
abrades.
[00071 b) Greens are required to be manufactured to raised structures during
the
raised formation of surface, industrialization can be realized only after
tremendous
investment is applied to original production equipment for technological
transformation as
the current formation equipment, molds and roaster charging are inadaptable.
The raised
parts on the surface of cathode are liable to cause cracked rejects even
subsequent to the
technological transformation.
[00081 c) Structural reinforcement is not implemented on the weak parts of
cathode
junction.
100091 d) It can be regarded as a misguidance that mixture or precipitate of
thick
cryolite melt alumina, which can be formed between raised walls at the bottom
of cathode,
is favorable for prolonging the service life of the electrolytic cell;
instead, this could only
increase electric resistivity at the bottom of the electrolytic cell and
generates unnecessary
power consumption.
[00101 2. China Patent, Name: Novel Cathode-structured Aluminum Electrolytic
Cell
Capable of Reducing Abrasion of Raised Parts of Cathode, Application (Patent)
Number:
200910248884.1, Classification Number: C25C3/08 (2006.1) I Applicant (Patent
Right):
FENG, Naiyang, Address: 11-3, Qixiang 2#, Hubei Road, Nanhuwang, Heping
District,
Shenyang City, Liaoning Province, Abstract: A novel cathode-structured
aluminum
electrolytic cell capable of reducing the abrasion of raised parts of cathode
is characterized
in that: a raised structure, known as length-direction raised part, is
processed on the edge of
each cathode carbon block in the length direction; or a raised structure
perpendicular to the
length direction of the cathode carbon block, known as width-direction raised
part, is
processed at the upper part of each cathode carbon block; or the length-
direction raised part
and the width-direction raised part are simultaneously processed at the upper
edge of the
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cathode carbon block. The middle part of the cathode carbon block is inlaid
with a layer of
wallboard made of refractory material, the wallboard forms, with the raised
parts of the
cathode carbon block, an integral raised part having the effect of reducing
flow rate of
aluminum electrolyte, lessening fluctuation of aluminum electrolyte and
enhancing
steadiness of the level of the aluminum electrolyte in electrolytic cell, and
after the raised
parts of the cathode carbon block are abraded, the wallboard made of
refractory material
can continuously play the role of reducing flow rate of aluminum electrolyte
owing to the
smaller electrochemical abrasiveness than carbon. Claims: A novel cathode-
structured
aluminum electrolytic cell capable of reducing the abrasion of raised parts of
cathode,
characterized in that: a raised structure, known as length-direction raised
part, is processed
on the edge of each cathode carbon block in the length direction; or a raised
structure
perpendicular to the length direction of the cathode carbon block, known as
width-
direction raised part, is processed at the upper part of each cathode carbon
block; or the
length-direction raised part and the width-direction raised part are
simultaneously
processed at the upper edge of the cathode carbon block; the three structures
are as below:
(1) the length-direction raised part, which has the raised height ranging from
10 to 18
centimeters and the raised width ranging from 5 to 15 centimeters in the
length direction, is
processed and also positioned on the edge of each cathode carbon block in the
length
direction, and the horizontal distance between the outer surface of the length-
direction
raised part and the edge of the cathode carbon block is from 1 to 3
centimeters, a middle
seam of two adjacent cathode carbon blocks are in tamped connection with each
other
through carbon tamping paste which has the height equal to that of the cathode
carbon
block, a wallboard made of refractory material is laid on the upper surface of
the tamping
paste of two adjacent cathode carbon blocks, and between every two adjacent
cathode
carbon blocks, the raised parts on the edge of the two adjacent cathode carbon
blocks in the
length direction and the wallboard made of refractory material constitute an
integral
length-direction raised part; (2) the length-direction raised part and the
width-direction
raised part are simultaneously processed at the upper part of the cathode
carbon block with
the width-direction raised part being positioned between the two integral
length-direction
raised parts described above and being integrated with the cathode carbon
block, and on
each cathode carbon block, the distance between the width-direction raised
part and the
integral length-direction raised parts adjacent thereto is from 5 to 10
centimeters; and (3)
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the width-direction raised parts are processed at the upper part of the
cathode carbon block,
and on each cathode carbon block, the distance between every two width-
direction raised
parts is from 20 to 40 centimeters, the height and the width of the width-
direction raised
parts are respectively from 10 to 18 centimeters and from 18 to 30
centimeters, and the
length of the width-direction raised parts is consistent with or smaller by 2
to 6 centimeters
than the width of the cathode carbon block.
[00111 In addition to the technical problems same as the patent 1, the
invention
also has the problem that the use of refractory material, i.e. non-conductive
material,
inevitably leads to the increase of electric resistivity of cell to further
increase power
consumption, which departs from the energy saving objective.
[00121 3. China Patent, Name: Components of Hard Graphitized Cathode Carbon
Block and Manufacturing Method thereof, Application (Patent) Number:
200910210043.1,
Application Date: 2009.11.04, Applicant (Patent Right): Luoyang Xin'an
Electric Power
Group Wanji Graphite Product Co., Ltd., Abstract: The invention discloses
components of
a hard graphitized cathode carbon block for aluminum electrolytic cell and a
manufacturing method thereof: a manufacturing method of the graphitized
cathode carbon
block, containing 15 to 17% of binder and 83 to 85% of electrically calcined
anthracite,
comprises the following steps of, smashing-screening-material mixing-kneading-
material
cooling-vibratory compaction-roasting- graphitization- machining; according to
the
invention, the abrasiveness of carbon block is reduced owing to the large
intensity of
carbon block, which is favorable for prolonging the service life of
electrolytic cell; and the
fracture sensitivity of carbon block is reduced owing to the excellent
deformation ability
thereof; and in the aspect of electrical properties, lower electric
resistivity is achieved to
reduce cathode drop, therefore, the purpose of better saving energy and
lowering
consumption is reached.
[00131 4. China Patent, Name: Abrasion-Resistant Graphitized Cathode Carbon
Block
for Aluminum Electrolytic Cell and Manufacturing Method thereof, Application
(Patent)
Number: 200910167718.9 Application Date: 2009.9.23, Applicant (Patent Right):
Sichuan
Guanghan Shida Carbon Co., Ltd. Abstract: The invention discloses an abrasion-
resistant
graphitized cathode carbon block for aluminum electrolytic cell and a
manufacturing
method thereof, relating to the field of nonmetal material of metallurgical
engineering
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material. According to the invention, high-sulfur petroleum coke with the
sulfur content
reaching 1 to 3% is used as one of the raw materials for manufacturing the
graphitized
cathode carbon block, and the proportions of the raw materials are as below:
80 to 85% of
high-sulfur petroleum coke with the sulfur content reaching 1 to 3%, and 15 to
20% of
modified coal pitch; during working operation, secondary high temperature
calcination is
adopted to effectively remove the sulfur in the high-sulfur petroleum coke;
the working
operations of impregnation and secondary roasting in the prior art are
replaced by large
vibratory compaction and lengthwise graphitization technologies; the
graphitization time
of products is reduced by over 50%, thereby reducing energy consumption and
cost. The
high-sulfur petroleum coke, an inferior raw material which can only be used as
fuel or
sintering aid originally, is effectively utilized. The manufactured abrasion-
resistant
graphitized cathode carbon block has high intensity, low porosity and good
resistance to
washout and abrasion of aluminum electrolyte, enhances the service life of
electrolytic cell,
and is suitable for the use as cathode lining of large electrolytic cell, and
especially for the
use in the electrolytic cell with over 400kA.
[00141 5. China Patent, Name: Graphitized Cathode Carbon Block for Aluminum
Electrolytic Cell, Application (Patent) Number: 200810068782.7, Application
Date:
2008.6.19, Applicant (Patent Right): Aluminum Corporation of China Limited,
Abstract:
The invention discloses a graphitized cathode carbon block for aluminum
electrolytic cell,
which consists of calcined coke and mixed pitch, wherein the calcined coke
accounts for
81 to 83% of the total weight of the graphitized cathode carbon block and the
mixed pitch
accounts for 17 to 19%. The mixed pitch consists of modified pitch and tar
with the
modified pitch accounting for 78 to 82% of the total weight of the mixed pitch
and the tar
accounting for 18 to 22%. The grain size of the calcined coke is smaller than
4.6
millimeters, wherein the granular grain size ranging from 4.5 to 3 millimeters
accounts for
15.5+2%, the granular grain size ranging from 3 to 1 millimeter accounts for
15 2%, and
the granular grain size smaller than 1 millimeter accounts for 21+2%; and
powder accounts
for 48.5 2%. The grain size of the calcined coke is 200 meshes accounting for
50 3%.
Compared with the prior art, the invention reduces the electric resistivity of
cathode carbon
block prominently, enhances the electric conductivity of cathode paste and
raises sodium
corrosion resistance of cathode carbon block, so that the quality of the
graphitized cathode
carbon block product is remarkably enhanced, the surrounding environment of
aluminum
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electrolysis factory building is improved, the cell voltage is reduced, the
service life of
aluminum electrolytic cell is prolonged, and energy consumption and
manufacturing cost
are lowered, etc.
[00151 6. China Patent, Name: Graphitized Cathode Production Technology,
Application (Patent) Number: 200410040135.7 Application Date: 2004.7.2,
Applicant
(Patent Right): Guiyang Aluminum Magnesium Design & Research Institute,
Abstract:
The invention discloses a graphitized cathode production technology, which
comprises the
steps of: selecting and mixing petroleum coke and pitch coke, calcining,
smashing and
screening the mixture, mixing and then adding hard pitch binder to the
mixture, kneading
and processing the mixture into a carbon block blank shape of the cathode
required by
electrolytic cell, and carbonizing the pitch binder by means of fusing to
obtain graphitized
cathode carbon block. The invention has the advantages of superior mechanical,
electrical
and thermal properties and is particularly suitable for the use in large
electrolytic cell.
[00161 Taken together, the patents 3-6 include the following defects:
[00171 1) Reinforced material and thickening material are not used in formula,
so the
compactness is inferior and the intensity is low.
[00181 2) Large grain size (4 millimeters at most) of the raw materials in
formula
leads to low density, poor homogeneousness and inferior abrasion and washout
resistances.
[00191 3) Introduction of no alloy additive not only results in the limited
reduction
of cathode drop in the aspect of electrical properties, but also limits energy
saving and
consumption reduction.
[00201 4) Since the graphitization temperature is above 2100 C, the
optimization for
performance indexes and the reduction for defects of the internal structure of
product
cannot be realized.
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SUMMARY OF THE INVENTION
[00211 Given the problems described above, the invention aims at providing a
novel
combined graphitized irregular cathode for aluminum, which can be prepared by
current
equipment at low cost, has long service life of stop blocks (as long as
electrolytic cell),
simultaneously implements structural reinforcement on weak parts of the
junction of two
cathode body blocks, and solves the technical problem that aluminum
electrolyte is liable
to leakage from the junction of two cathode body blocks, and further providing
a
graphitized cathode stop block which is indispensable for constituting the
novel combined
graphitized irregular cathode for aluminum and has simple modified operation,
high
density, high intensity and long service life, and a preparation method
thereof.
[00221 The invention is implemented in such a manner that:
[00231 A novel combined graphitized irregular cathode for aluminum comprises
body
blocks and graphitized cathode stop blocks, longitudinal edges of the body
blocks are
symmetrically provided with two groups of grooves, the graphitized cathode
stop blocks
made of the material different from the body blocks are inlaid inside the
groove combined
by the two grooves in a manner of bridging over a junction seam between the
two body
blocks, and the graphitized cathode stop blocks are tamped on the body blocks
through
paste, i.e. the stop blocks are inlaid on the junction seam between the two
cathode body
blocks in a manner of bridging over the cathode. The external dimension of the
body
blocks and the stop blocks, the inlaying manner and the machining requirement
can be
determined in accordance with the dimension of electrolytic cell and the
installed capacity
of transformer.
[00241 The novel combined graphitized irregular cathode for aluminum described
above is characterized in that: the body blocks are made of carbon block
material for
common aluminum electrolysis and the stop blocks are made of graphitized
material for
aluminum electrolysis.
[00251 The distance between the graphitized cathode stop blocks described
above and
the transverse outer edge of the body blocks is from 300 to 380 millimeters so
that the stop
blocks are not damaged or loosened by collision during the operation or the
maintenance of
the anode of the aluminum electrolytic cell, and the spacing between the two
graphitized
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cathode stop blocks is from 300 to 350 millimeters so as to facilitate the
charging of the
electrolytic cell.
[00261 The novel combined graphitized irregular cathode for aluminum described
above is characterized in that: the junction seam between the body blocks is
tamped
through paste.
[00271 The novel combined graphitized irregular cathode for aluminum described
above is characterized in that: the grooves are 100 to 150 millimeters deep
and 80 to 100
millimeters wide.
[00281 The novel combined graphitized irregular cathode for aluminum described
above is characterized in that: the graphitized cathode stop blocks have
rectangular or
convex cross section; and in case of the convex cross section, chamfer angles,
from 135 to
175 and 30 to 60 millimeters high, are arranged on the top end of the
graphitized cathode
stop blocks.
[00291 The graphitized cathode stop block constituting the novel combined
graphitized irregular cathode for aluminum is prepared from the following raw
materials in
parts by weight:
TiB2 alloy additive 1 to 8 parts;
calcined petroleum coke 40 to 85 parts;
Electrically calcined anthracite 1 to 40 parts;
Coal pitch 15 to 25 parts;
SiC additive 1 to 15 parts.
100301 The graphitized cathode stop block described above is characterized in
that: the
grain size of both the calcined petroleum coke and the electrically calcined
anthracite is 0
to 2 millimeters.
[00311 Both the TiB2 (titanium boride) additive and the SiC (silicon carbide)
additive
described above are selected from commercially pure additives with the grain
size smaller
than or equal to 40 microns, and these two additives are easily commercially
available for
the skilled in this art.
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[00321 The calcined petroleum coke in raw materials reduces the ash content
and
enhances the electrical conductivity of product by means of low ash content
and easy
graphitization property of petroleum coke.
[00331 The electrically calcined anthracite in raw materials enhances the
washout
resistance, the density and the intensity of product by means of low electric
resistivity and
high compactness thereof.
[0034] The coal pitch in raw materials is used as binder for binding various
materials,
in order to form a firm carbon binding grid.
[00351 The SiC (silicon carbide) additive in raw materials is used as
reinforcement for
pore pinning inside product, in order to enhance the density and the intensity
of product.
[00361 The TiB2 (titanium boride) additive in raw materials is capable of
stabilizing
the fluctuation of aluminum electrolyte owing to the humidification property
thereof for
molten aluminum electrolyte, and simultaneously realizes lower electric
resistivity in the
aspect of electrical properties to further lower cathode drop, reduce
electrode distance and
save power.
[00371 The method for preparing the graphitized cathode stop block comprises
the
following steps of:
(1) Smashing calcined petroleum coke and electrically calcined anthracite;
(2) Screening the smashed calcined petroleum coke and electrically calcined
anthracite according to the requirement of grain size;
(3) material mixing: the electrically calcined anthracite, the calcined
petroleum
coke, the Pt boron/titanium alloy additive and the SiC additive are put in a
kneading ladle according to the proportion of the raw materials thereof;
(4) kneading: dry kneading is implemented for 20 to 40 minutes at the
temperature
ranging from 40 to 165 C; and wet kneading is implemented for 35 to 50
minutes at the temperature ranging from 150 to 170 C;
(5) Forming: the kneaded raw materials are put in a mold for formation;
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(6) roasting: the formed semi-finished product is subjected to primary
roasting,
then to high pressure impregnation with molten coal pitch and finally to
secondary roasting at low temperature ranging from 700 to 850 C; the degree of
vacuum of the high pressure impregnation is not less than -0.092MPa and the
pressure thereof is not less than 1.5MPa;
(7) low-temperature graphitization: the temperature ranges from 1800 to 2000
C;
(8) Machining: machining is performed according to the dimensional requirement
of finished product to obtain the graphitized cathode stop block.
[00381 Compared with the prior art, the novel combined graphitized irregular
cathode
for aluminum and the graphitized cathode stop block thereof according to the
invention
have the following advantages of:
(1) the energy-saving graphitized irregular cathode is formed by inlaying stop
blocks on a junction seam between two cathode body blocks in a manner of
bridging over cathode, and through the raised stop blocks, the cathode can
stabilize the level of aluminum electrolyte to shorten the electrode distance
by
not less than 10 millimeters and reduce cell voltage by about 0.35 to 5V, thus
the purpose that the power consumption of electrolysis aluminum per ton is
saved by not less than 1000kWh is reached;
(2) inlaying the stop blocks in a manner of bridging over the cathode can not
only
avoid that grooving in the middle of the body blocks reduces the effective
thickness of the body blocks to further impact on the service life thereof,
but
can also implement reinforcement of local structure on the weak parts (the
junction seam) of the body blocks in order to prolong the service life of
electrolytic cell;
(3) the productions of the body block and the stop block are performed based
on
different materials, thereby achieving well-directed quality improvement and
simple implementation as well as lowering cost;
(4) No variation is applied to current body equipment, molds, furnace types
and the
like in the production process of the cathode, and operability is strong;
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(5) in use, grooving is simple and consistent with current aluminum
electrolysis
technologies;
(6) The graphitized cathode stop block is prepared based on the formula in
which
fine grains with the maximal grain size not more than 2 millimeters are
adopted,
thus the intensity, density, homogeneousness and corrosion and washout
resistances of product are enhanced;
(7) By introducing the reinforced and thickening materials (electrically
calcined
anthracite and SiC additive) into the graphitized cathode stop block, the
mechanical properties of product are further enhanced;
(8) with the TiB2 alloy additive added to the graphitized cathode stop block,
the
fluctuation of aluminum electrolyte can be stabilized owing to the
humidification property of TiB2 for molten aluminum electrolyte, and lower
electric resistivity in the aspect of electrical properties is simultaneously
realized to further lower cathode drop, thus the purpose of saving energy and
reducing consumption better is reached;
(9) The density and the intensity of product are further enhanced by adopting
high-
pressure impregnation and secondary roasting densification technologies for
the
graphitized cathode stop block;
(10) low temperature graphitization technology is adopted for the graphitized
cathode stop block in order to optimize the mechanical, electrical and thermal
properties as well as the performance indexes of product and to reduce the
defects of the internal structure of product;
(11) The invention can save energy by more than 1000kWh for more than 2200
days.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00391 Figure 1 is a stereogram of the novel combined graphitized irregular
cathode
for aluminum of the invention;
[00401 Figure 2 is a top view of the Figure 1;
[00411 Figure 3 is a right view of the Figure 1; and
[00421 Figure 4 is a process flow diagram of the graphitized cathode stop
block.
[00431 In the figures, 1 represents body block, 2 represents junction seam, 3
represents
graphitized cathode stop block, 4 represents groove and 5 represents top end
chamfer
angle.
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DETAILED DESCRIPTION OF THE INVENTION
[00441 Embodiment 1:
[00451 The preparation of the graphitized cathode stop block comprises the
following
steps that: 1 part of calcined anthracite and 40 parts of electrically
calcined petroleum coke
based on mass proportion are smashed; the smashed electrically calcined
anthracite and
calcined petroleum coke are screened according to requirement of grain size to
obtain
grains with the grain size of 0 millimeter; the screened electrically calcined
anthracite and
calcined petroleum coke, conforming to the requirement, are put in a kneading
ladle
together with 1 part of 40 microns commercially pure TiB2 additive and 1 part
of 40
microns commercially pure SiC additive, followed by material mixing; 15 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 20
minutes at 40 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
700 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
1800 C; and the
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block which is 120 millimeters high and 150
millimeters wide.
[00461 Shown as Figure 1, in the novel combined graphitized irregular cathode
for
aluminum according to the invention, the external dimension of the body blocks
and the
length of the stop blocks are determined in accordance with the dimension of
electrolytic
cell and the installed capacity of transformer; longitudinal edges of the body
blocks (1) are
symmetrically provided with two groups of grooves (4) which are 100
millimeters deep
and 80 millimeters wide, the distance between the grooves (4) and the
transverse outer
edge of the body blocks is 300 millimeters and the spacing between two grooves
(4) at the
same side is 300 millimeters; the graphitized cathode stop blocks (3), which
are made of
the material different from the body blocks, has rectangular cross section and
is 120
millimeters high and 150 millimeters wide, are inlaid inside the groove
combined by the
two grooves (4) in a manner of bridging over a junction seam (2) between the
two body
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blocks (1); and finally, the junction seam (2) between the two body blocks (1)
is tamped
through paste and the graphitized cathode stop blocks (3) are tamped on the
body blocks
(1) through paste as well.
[00471 Embodiment 2:
[00481 The preparation of the graphitized cathode stop block comprises the
following
steps that: 20 part of calcined anthracite and 606 parts of electrically
calcined petroleum
coke based on mass proportion are smashed; the smashed electrically calcined
anthracite
and calcined petroleum coke are screened according to requirement of grain
size to obtain
grains with the grain size of 1 millimeter; the screened electrically calcined
anthracite and
calcined petroleum coke, conforming to the requirement, are put in a kneading
ladle
together with 4 part of 30 microns commercially pure TiB2 additive and 7 part
of 30
microns commercially pure SiC additive, followed by material mixing; 20 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 30
minutes at 100 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
800 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
1900 C; and the
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block which is 190 millimeters high and 175
millimeters wide.
[00491 Shown as Figure 1, in the novel combined graphitized irregular cathode
for
aluminum according to the invention, the external dimension of the body blocks
and the
length of the stop blocks are determined in accordance with the dimension of
electrolytic
cell and the installed capacity of transformer; longitudinal edges of the body
blocks (1) are
symmetrically provided with two groups of grooves (4) which are 125
millimeters deep
and 90 millimeters wide, the distance between the grooves (4) and the
transverse outer
edge of the body blocks is 340 millimeters and the spacing between two grooves
(4) at the
same side is 325 millimeters; the graphitized cathode stop blocks (3), which
are made of
the material different from the body blocks, has rectangular cross section and
is 190
millimeters high and 175 millimeters wide, are inlaid inside the groove
combined by the
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16
two grooves (4) in a manner of bridging over a junction seam (2) between the
two body
blocks (1); and finally, the junction seam (2) between the two body blocks (1)
is tamped
through paste and the graphitized cathode stop blocks (3) are tamped on the
body blocks
(1) through paste as well.
[00501 Embodiment 3:
[00511 The preparation of the graphitized cathode stop block comprises the
following
steps that: 40 part of calcined anthracite and 85 parts of electrically
calcined petroleum
coke based on mass proportion are smashed; the smashed electrically calcined
anthracite
and calcined petroleum coke are screened according to requirement of grain
size to obtain
grains with the grain size of 2 millimeter; the screened electrically calcined
anthracite and
calcined petroleum coke, conforming to the requirement, are put in a kneading
ladle
together with 8 part of 20 microns commercially pure TiB2 additive and 15 part
of 20
microns commercially pure SiC additive, followed by material mixing; 25 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 40
minutes at 165 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
850 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
2000 C; The
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block, which has convex cross section, the overall
height of 260
millimeters, the overall width of 200 millimeters, the top end chamfer angles
(5) of 135
and the chamfer angle height of 30 millimeters.
[00521 Shown as Figure 1, in the one of novel combined graphitized irregular
cathodes
for aluminum according to the invention, the external dimension of the body
blocks and
the length of the stop blocks are determined in accordance with the dimension
of
electrolytic cell and the installed capacity of transformer; longitudinal
edges of the body
blocks (1) are symmetrically provided with two groups of grooves (4) which are
150
millimeters deep and 100 millimeters wide, the distance between the grooves
(4) and the
transverse outer edge of the body blocks is 380 millimeters and the spacing
between two
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17
grooves (4) at the same side is 350 millimeters; The graphitized cathode stop
blocks (3),
which are made of the material different from the body blocks and has convex
cross
section, the overall height of 260 millimeters, the overall width of 200
millimeters, the top
end chamfer angles (5) of 135 and the chamfer angle height of 30 millimeters,
are inlaid
inside the groove combined by the two grooves (4) in a manner of bridging over
the
junction seam (2) between the two body blocks (1);and finally, the junction
seam (2)
between the two body blocks (1) is tamped through paste and the graphitized
cathode stop
blocks (3) are tamped on the body blocks (1) through paste as well.
[00531 Embodiment 4:
[0054] The preparation of the graphitized cathode stop block comprises the
following
steps that: 10 part of calcined anthracite and 50 parts of electrically
calcined petroleum
coke based on mass proportion are smashed; the smashed electrically calcined
anthracite
and calcined petroleum coke are screened according to requirement of grain
size to obtain
grains with the grain size of 0.5 millimeter; the screened electrically
calcined anthracite
and calcined petroleum coke, conforming to the requirement, are put in a
kneading ladle
together with 3 part of 10 microns commercially pure TiB2 additive and 4 part
of 10
microns commercially pure SiC additive, followed by material mixing; 18 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 35
minutes at 150 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
780 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
1850 C; The
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block, which has convex cross section, the overall
height of 260
millimeters, the overall width of 200 millimeters, the top end chamfer angles
(5) of 150
and the chamfer angle height of 45 millimeters.
[0055] Shown as Figure 1, in the one of novel combined graphitized irregular
cathodes
for aluminum according to the invention, the external dimension of the body
blocks and
the length of the stop blocks are determined in accordance with the dimension
of
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NIIP002-1 CA
18
electrolytic cell and the installed capacity of transformer; longitudinal
edges of the body
blocks (1) are symmetrically provided with two groups of grooves (4) which are
150
millimeters deep and 100 millimeters wide, the distance between the grooves
(4) and the
transverse outer edge of the body blocks is 380 millimeters and the spacing
between two
grooves (4) at the same side is 350 millimeters; The graphitized cathode stop
blocks (3),
which are made of the material different from the body blocks and has convex
cross
section, the overall height of 260 millimeters, the overall width of 200
millimeters, the top
end chamfer angles (5) of 135 and the chamfer angle height of 30 millimeters,
are inlaid
inside the groove combined by the two grooves (4) in a manner of bridging over
the
junction seam (2) between the two body blocks (1);and finally, the junction
seam (2)
between the two body blocks (1) is tamped through paste and the graphitized
cathode stop
blocks (3) are tamped on the body blocks (1) through paste as well.
[0056] Embodiment 5:
[0057] The preparation of the graphitized cathode stop block comprises the
following
steps that: 35 part of calcined anthracite and 75 parts of electrically
calcined petroleum
coke based on mass proportion are smashed; the smashed electrically calcined
anthracite
and calcined petroleum coke are screened according to requirement of grain
size to obtain
grains with the grain size of 1.8 millimeter; the screened electrically
calcined anthracite
and calcined petroleum coke, conforming to the requirement, are put in a
kneading ladle
together with 6 part of 25 microns commercially pure TiB2 additive and 12 part
of 25
microns commercially pure SiC additive, followed by material mixing; 22 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 40
minutes at 160 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
840 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
1820 C; The
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block, which has convex cross section, the overall
height of 260
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19
millimeters, the overall width of 200 millimeters, the top end chamfer angles
(5) of 175
and the chamfer angle height of 60 millimeters.
[00581 Shown as Figure 1, in the one of novel combined graphitized irregular
cathodes
for aluminum according to the invention, the external dimension of the body
blocks and
the length of the stop blocks are determined in accordance with the dimension
of
electrolytic cell and the installed capacity of transformer; longitudinal
edges of the body
blocks (1) are symmetrically provided with two groups of grooves (4) which are
150
millimeters deep and 100 millimeters wide, the distance between the grooves
(4) and the
transverse outer edge of the body blocks is 380 millimeters and the spacing
between two
grooves (4) at the same side is 350 millimeters; The graphitized cathode stop
blocks (3),
which are made of the material different from the body blocks and has convex
cross
section, the overall height of 260 millimeters, the overall width of 200
millimeters, the top
end chamfer angles (5) of 1750 and the chamfer angle height of 60 millimeters,
are inlaid
inside the groove combined by the two grooves (4) in a manner of bridging over
the
junction seam (2) between the two body blocks (1); and finally, the junction
seam (2)
between the two body blocks (1) is tamped through paste and the graphitized
cathode stop
blocks (3) are tamped on the body blocks (1) through paste as well.
[00591 Embodiment 6:
[00601 The preparation of the graphitized cathode stop block comprises the
following
steps that: 30 part of calcined anthracite and 70 parts of electrically
calcined petroleum
coke based on mass proportion are smashed; the smashed electrically calcined
anthracite
and calcined petroleum coke are screened according to requirement of grain
size to obtain
grains with the grain size of 1.5 millimeter; the screened electrically
calcined anthracite
and calcined petroleum coke, conforming to the requirement, are put in a
kneading ladle
together with 5 part of 35 microns commercially pure TiB2 additive and 10 part
of 35
microns commercially pure SiC additive, followed by material mixing; 22 parts
of molten
coal pitch and the well-mixed raw materials above are subjected to dry
kneading for 50
minutes at 170 C; the kneaded raw materials are put in a mold for formation;
the formed
semi-finished product is subjected to primary roasting, then to high pressure
impregnation
with molten coal pitch and finally to secondary roasting at low temperature of
820 C,
wherein the degree of vacuum of the high pressure impregnation is not less
than -
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NIIP002-1 CA
0.092MPa and the pressure thereof is not less than 1.5MPa; after the secondary
roasting,
the semi-finished product is subjected to low-temperature graphitization at
1950 C; The
graphitized crude finished product is cooled and then subjected to machining
to form the
graphitized cathode stop block, which has convex cross section, the overall
height of 260
millimeters, the overall width of 200 millimeters, the top end chamfer angles
(5) of 175
and the chamfer angle height of 60 millimeters.
[00611 Shown as Figure 1, in the one of novel combined graphitized irregular
cathodes
for aluminum according to the invention, the external dimension of the body
blocks and
the length of the stop blocks are determined in accordance with the dimension
of
electrolytic cell and the installed capacity of transformer; longitudinal
edges of the body
blocks (1) are symmetrically provided with two groups of grooves (4) which are
150
millimeters deep and 100 millimeters wide, the distance between the grooves
(4) and the
transverse outer edge of the body blocks is 380 millimeters and the spacing
between two
grooves (4) at the same side is 350 millimeters; The graphitized cathode stop
blocks (3),
which are made of the material different from the body blocks and has convex
cross
section, the overall height of 260 millimeters, the overall width of 200
millimeters, the top
end chamfer angles (5) of 175 and the chamfer angle height of 60 millimeters,
are inlaid
inside the groove combined by the two grooves (4) in a manner of bridging over
the
junction seam (2) between the two body blocks (1);and finally, the junction
seam (2)
between the two body blocks (1) is tamped through paste and the graphitized
cathode stop
blocks (3) are tamped on the body blocks (1) through paste as well.
