Title of Invention

PROCESS FOR PREPARING BISMUTH OXIDE, AND THE APPARATUS THEREFOR

Abstract A method of preparing bismuth oxide and an apparatus therefor are disclosed. The method includes: melting metal bismuth, transporting the melted metal bismuth to an open first reactor and oxidizing the melted metal bismuth while stirring at the temperature of 300-650°C and transporting bismuth oxide and un-reactd material to an closed second reactor through a screw and oxidizing the bismuth oxide and an un-reacted material while rotating the closed second reactor at the temperature of 300-600°C with supply of air oxygen.
Full Text

Technical Field
The present invention relates to a method of preparing bisrruth oxide and an
apparatus therefor. More particularly, the present invention relates to a method of
preparing bisrruth oxide by melting metal bismuth at a low temperature, stirring the
melted bismuth in an open reactor at 300 - 650°C, and oxidizing the obtained product
in a closed reactor by supplying oxygen, and an apparatus therefor.
Bismuth oxide generally refers to bismuth trioxide (Bi2O3 ) having high electric con-
ductivity, and is used variously for disinfectant, magnet, glass, gum, anti-flame paper,
catalyst and so on. Accordingly, demand of bismuth oxide is increasing, and especially
demand for bisrnuth oxide with high-purity is increasing in the electronic industry.
Bismuth oxide is classified into 4 isomer types of α-type, β-type, y-type, and S-type
according to its crystal structure, and a-bismuth oxide is generally used in the industry.
Background Art
Bismuth oxide is conventionally prepared by one of the following methods:
oxidizing fine powder bismuth by burning bismuth or injecting it into a heated zone
(Patent Reference 1); dissolving metal bismuth in sodium nitrate by heating and
passing chlorine gas (Patent Reference 2); neutralizing aqueous solution of bismuth
nitrate with sodium hydroxide or potassium hydroxide, and precipitating the
neutralized solution at 40 - 70X to obtain needle-crystalline bismuth oxide (Patent
Reference 3); obtaining bismuth mono:carboxylic acid complex in an aqueous solution
by adding mono-carboxylic acid to trivalent bisrruth ions, further precipitating the
complex by adding an alkali in an aqueous solution, and separating the complex from
the solution, and obtaining fine spherical bismuth oxide particles by firing the
separated the ccmplex(Patent Reference 4); vaporizing bismuth by heating at a high
temperature, and supplying air to the vaporized bismuth (Patent Reference 5);
obtaining bismuth nitrate solution by adding nitric acid and hydrogen peroxide to
bismuth metal grains or powder, separating the precipitant by adding sodium
hydroxide to the solution and heating, and washing, drying, classifying the separated
precipitant ,and obtaining bismuth oxide. (Non-patent Reference 1); oxidizing fine
particle metal bisrruth by injecting air and heating at 850 - 900oC (Non-patent

Reference 1); and other methods such as oxidizing metal bismuth at 750 - 800°C,
pyrolyzing bismuth carbonate, and adding alkaline metal hydroxide to bismuth salt
solution (Non-patent Reference 2).
Patent Reference 1: US Patent No. 1,318,336
Patent Reference 2: US Patent No. 1,354,806
Patent Reference 3: Japanese Patent Publication
No.Sho47-11335
Patent Reference 4: US Patent No. 4,873,073
Patent Reference 5: Japanese Patent Publication No. Sho61-136922
Non-patent Reference 1: JOM; Apr 2002; 54,4; ABI/INFORM Trade & Industry
Non-patent Reference 2: Ullman's Encyclopedia of Industrial Chemistry, Vol. 5, pp.
185-185
Disclosure of Invention
Technical Problem
In the prior art, although Patent Reference 1 does not disclose the temperatures of
melting and oxidizing bismuth. Referring to Non-patent References 1 and 2, this
reaction is supposed to be executed at 750 - 900oC. However, a method of performing
a reaction at a high temperature requires a high energy cost, and a final product
prepared according to the method may lose competitiveness in the market.
The methods of preparing bismuth oxide by using a bismuth salt, such as bismuth
nitrate, according to the Patent References 3 and 4 must be performed in two steps of
preparing bismuth nitrate and obtaining bismuth oxide from the prepared bismuth
nitrate, whose process is complicated and not economical. In the case of preparing
bismuth oxide from purchased bismuth nitrate, the price of bismuth nitrate is high and
bismuth nitrate is not easily available. Therefore it may result in a high production
cost.
Further in a wet process of the Patent References 3 and 4, by-products must be
eliminated by washing after separation of bismuth oxide. Therefore, this process may
cause environmental pollution, and water treatment cost of washing and reaction
effluent is high. Further, operating environment of the process is inferior and small
amount of residual acids contained in the prepared bismuth oxide may deteriorate
quality of the bismuth oxide. Therefore, it cannot meet requirement of high-purity
bismuth oxide.

A method of preparing bismuth oxide according to the Patent Reference 5 utilizes a
vapor-phase reaction and requires high energy consumption, long processing time and
precision facilities. Further, the particle size of prepared bismuth oxide is extremely
fine (equivalent to several nanometers). Therefore, manufacturing and maintenance
costs of high temperature resistant filters used for collection of the prepared fine
bismuth oxide are very high, and thereby a production facility of this method becomes
expensive and uneconomical.
Technical Solution
The present invention has been made in view of the above problems, and the present
invention provides a method of preparing high-purity abismuth oxide with a high yield
by melting bismuth metal ingot at a temperature higher than 300°C (preferably at 400 -
450°C), transporting the melted bismuth metal to a first reactor that is open to air,
oxidizing bismuth while stirring at the temperature at 300 - 650°C, collecting bismuth
oxide in a collecting tank having an exhaust fan, and reacting the collected bismuth
oxide with oxygen again in a second reactor at 300 - 600°C.
Advantageous Effects
According to the present invention, high-purity α bismuth oxide may be prepared
economically by melting metal bismuth at a temperature near the melting point of
bismuth, which is much lower than a conventional condition (700°C or higher),
oxidizing the melted bismuth, and oxidizing the bismuth oxide again at a relatively low
temperature of 300 - 650°C in air or oxygen gas environment.
Ah apparatus for preparing high-purity bismuth oxide according to the present
invention has advantages of simple operation, high efficiency, and easy maintenance,
because bismuth oxide obtained from a first reactor is collected by a collecting device
having an exhaust fan and un-reacted bismuth is oxidized again by a second reactor in
air or oxygen gas environment.
Further, in the apparatus for preparing high-purity bismuth oxide according to the
present invention, the production rate of bismuth oxide may be controlled by installing
a storage tank between the collecting tank and second reactor.
Brief Description of the Drawings
FIG. lis a schematic view showing a configuration of an apparatus for preparing
bismuth oxide according to an exemplary embodiment of the present invention.
FIG. 2 is an enlarged sectional view showing a detailed structure of a first reactor in
the apparatus of FIG. 1.

FIG. 3 is an enlarged sectional view showing a detailed structure of a second reactor
in the apparatus of FIG. 1.
FIG. 4 is a graph showing an X-ray diffraction analysis result of bismuth oxide
obtained by a preparation method according to another exemplary embodiment of the
present invention.
FIG. 5 is another graph showing an X-ray diffraction analysis result of bismuth oxide
obtained by a preparation method according to another exemplary embodiment of the
present invention.
Best Mode for Carrying Out the Invention
Hereinafter, exemplary embodiments of the present invention are described in detail
with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a configuration of an apparatus for preparing
bismuth oxide according to an exemplary embodiment of the present invention, FIG. 2
is an enlarged sectional view showing a detailed structure of a first reactor in the
apparatus of FIG. 1, and FIG. 3 is an enlarged sectional view showing a detailed
structure of a second reactor in the apparatus of FIG. 1.
Referring to FIG. 1, the apparatus for preparing bismuth oxide includes: a melting
tank 110 for melting metal bismuth at a high temperature; an open first reactor 120
having an internal impeller 121 driven by a motor 122 for primary oxidation of the
melted metal bismuth; a collecting device 130 having an exhaust fan 134 for collecting
bismuth oxide in the first reactor 120 by using differential pressure; a closed second
reactor 150 having an internal screw driven by a motor 151 and an oxygen inlet for
secondary oxidation of the bismuth oxide collected by the collecting device 130; and a
pulverizer 160 for pulverizing the obtained fine powder bismuth oxide.
The melting tank 110 is a device for melting metal bismuth, and the temperature
inside the melting tank 110 may be maintained at a temperature higher than the
melting point of bismuth (27It!). However, the temperature inside the melting tank
110 is preferably maintained at the temperature of '300oC or higher than 300°C for high
reaction speed and productivity considering* that the temperature of the first reactor 120
at 300--650°C;
In particular, the temperature inside the first reactor 120 is preferably maintained
constantly by supplying hot air so that the hot air may contact with the surface of the
melted bismuth supplied into the first reactor 120. When the melted bismuth is
supplied into the first reactor 120, the hot air reduces scale formation at the inner wall
of the first reactor 120 and at the shaft of the impeller 121, which is caused by a

difference between the temperature of melted bismuth in the first reactor 120 and the
temperature of melted bismuth supplied from the melting tank 110. The temperature of
the hot air may be 200 - 450oC and is not particularly limited. However, the
temperature of hot air is preferably 300-450°C.
The first reactor 120 is controlled to maintain the reaction temperature at 300 - 600°C
and primarily oxidizes the melted bismuth supplied from the melting tank 110. The
melted bismuth in the first reactor 120 is oxidized while stirring with the impeller 121
driven by the motor 122.
The impeller 121 rotates on a vertical axis, and the distance between the lower
surface of the impeller 121 and the bottom inner surface of the first reactor 120 is
preferably set as small as possible. In a case that the distance between the lower
surface of the impeller 121 and the bottom inner surface of the first reactor 120 is
large, stirring is not sufficient, and un-yeacted bismuth may deposit on the bottom
inner surface of the first reactor 120.
The temperature inside the first reactor 120 is maintained constantly by supplying
hot air so that the hot air may contact with the surface of the melted bismuth supplied
into the first reactor 120. When the melted bismuth is supplied into the first reactor
120, the hot air reduces scale formation at the inner wall of the first reactor 120 and at
the axis of the impeller 121, which is caused by a difference between the temperature
of melted bismuth in the first reactor 120 and the temperature of melted bismuth
supplied from the melting tank 110.
Air or oxygen gas may be supplied into the first reactor 120 to accelerate oxidation
of bismuth, as shown in FIG. 2. Referring to FIG. 2A, an injection pipe 122 is installed
at a proper position in the first reactor 120 to supply air or oxygen gas from an air/
oxygen supplier (not shown). The outlet of the injection pipe 122 is submerged in the
melted bismuth such that the air or oxygen gas is directly injected into the melted
bismuth.
Alternatively, the injection pipe 122 may be installed inside the axis of the impeller
121, and air or oxygen gas may be injected through an inner space of the impeller 121,
as shown in FIG. 2B. Accordingly, the structure of the first reactor 120 may be
simplified, because the injection pipe 122 is not installed aside from the impeller 121
in the first reactor 120. In this case, a powerful motor is necessary for driving the
impeller 121, because a large amount of driving power is required for stirring of
melted bismuth in the first reactor 120.
The collecting device 130 is controlled to collect bismuth oxide formed in the first

reactor 120, and includes a settling tank 131 for stabilizing bismuth oxide supplied
from the first reactor 120, a cyclone 132 for circulating air to be sucked by an exhaust
fan 134 and generating air turbulence, and a collecting tank 133 having an exhaust fan
134 for collecting bismuth oxide. Further, a screw 135 for transporting bismuth oxide
is installed at the bottom of the settling tank 131, cyclone 132 and collecting tank 133.
The collecting device 130 works as follows:
If the exhaust fan 134 is driven, the pressure inside the collecting tank 133 is dra-
matically reduced, and air of the first reactor 120 flows towards the collecting tank 133
through the settling tank 131 and cyclone 132. Accordingly, differential pressure is
formed in the first reactor 120.
The air turbulence generated by the cyclone 132; accelerates airflow speed, and
thereby the differential pressure in the first reactor 120 can be increased quickly.
According to the differential pressure generated in the first reactor 120, bismuth
oxide having a smaller specific gravity than metal bismuth flows towards the settling
tank 131 of the collecting device 130, seme stabilized bismuth oxide particles fall
down and are transported by the screw 135. Seme bismuth oxide particles collided
with the inner wall of the cyclone 132 by a centrifugal force fall down along the inner
wall of the cyclone 132 and are transported by the screw 135. The remaining bismuth
oxide particles move into the collecting tank 133, and are finally collected by the
screw 135 and transported to the next device.
As bismuth oxide formed in the fust reactor 120 moves towards the collecting device
130 and the account of bismuth in the first reactor 120 is reduced, the load of the motor
122 driving the impeller 121 is also reduced: Accordingly, a feeding rate of melted
bismuth to the first reactor 120 may be controlled by detecting the load of the motor
122, and the amount of reacted and un-reacted bismuth in the first reactor 120 may be
maintained properly all the time.
The storage tank 140 stores bismuth oxide transported by the screw 135. If
necessary, a filtering process may be added to remove impurities frcm the transported
bismuth oxide.
Bismuth oxide particles exhausted from the collecting device 130 may directly be
transported to the closed second reactor 150 without passing through the storage tank
\ 40, as shown by a dotted line in FIG. 1. The storage tank 140 is an optional item in
the present invention.
The closed second reactor 150 is controlled to oxidize again reactant oxidized in the
first reactor 120 and performs oxidization of an un-reacted material (residual bismuth)

by using a screw (not shown) driven by the motor 151 in an closed tank while
maintaining the temperature at 300°C -. 600°C
Further, rapid oxidation may be induced by supplying oxygen gas into the closed
second reactor 150. The pressure of the oxygen gas supplied to the closed second
reactor 120 may differ according to a condition of the second reactor 150. If pure
oxygen is supplied at the pressure of 1 - 2.5 Kgf/cm2 , rapid oxidation may be achieved
without using the closed second reactor for high-pressure.
The closed second reactor 150 may be installed by using an eccentric axis, as shown
in FIG. 3, to accelerate the oxidation in the second reactor 150. That is, if a center axis
153 of the closed second reactor 150 is installed eccentrically to a driving axis 152 of a
motor 151, oxidation may be accelerated by a shaking effect while the closed second
reactor 150 is rotating.
The pulverizer 160 pulverizes the bismuth oxide oxidized in the closed second
reactor 150. A filtering process may be added prior to a pulverizing process to remove
impurities from bismuth oxide.
Mode for the Invention
Hereinafter, exemplary embodiments of the present invention are described in detail
with reference to the accompanying drawings. However, the present invention is not
limited to the described exemplary embodiments.
Example 1 (Primary Oxidation)
Bismuth metal ingot having the purity of 99.99% at temperature of 400 - 450°C was
continuously supplied at a feeding rate of 45kg/hr to the melting tank 110 having the
capacity of 1 m while maintaining the temperature at 300 - 400°C. The temperature of
the first reactor 120 having the capacity of 300 liter to which hot air is supplied was
maintained at 300°C. The impeller 121 was driven at the speed of 50 -100 rpm. The
suction differential pressure at settling tank 131 or cyclone 132 was maintained at
20mm H2O by an exhaust fan connected to the collecting tank 130. Melted bismuth
was transported to the first reactor 120 at the feeding rate of 45 Kg/hr and oxidized
while Stirling with the impeller 121.
The above procedure was repeated by changing the temperature of the first reactor
120 to 350,400,450, 500,550, 600, and 650°C. Before transporting to the collecting
device 130, samples of the reactant were collected to measure the contents of un-
reacted bismuth in the samples. The result of the measurement is shown in percentages
in Table 1.

Example 2
The same method as Example 1 was performed in Example 2 except that bismuth
metal ingot was supplied at the feeding rate of 30 Kg/hr. The weights of un-reacted
bismuth in collected samples were measured, and the result is shown in percentages in
Table 1.

Table 1 shows that the degree of oxidation increases as the reaction temperature
increases. However, it was observed that aggregation of reactant is induced at a
temperature higher than 650°C. It was also observed that the degree of oxidation
decreases as the feeding rate of the raw material increases, because retention time of
the raw material in the reactor decreases. In contrast, it was observed that the degree of
oxidation increases as a feeding rate of the raw material decreases. Accordingly, the
capacities of the reactor and the corresponding heating medium must be increased to
increase the feeding rate of the raw material.
In the above examples, oxidation may be performed at 300 - 350°C, but it takes long
time to complete the reaction because the degree of oxidation is as low as 25 - 50%.
Accordingly, oxidation is preferably performed at 450 - 650°C. If the feeding rate of
melted bismuth is slow, the oxidation speed increases, because the load of the motor
driving the impeller becomes low and the contact surface of bismuth for reacting with

oxygen in the air is increased.
Example 3
Reaction product obtained from the first reactor 120 at the reaction temperature of
650°C and containing 0.04% un-reacted bismuth according to Example 2 was
transported through the settling tank 131, cyclone 132 and collecting tank 133. Heavy
particles transported through lower hoppers of the (settling tank 131 and cyclone 132
were transported by the screw 135. Light particles transported to the collecting tank
133 were also transported by the screw 135. The heavy and light particles on the screw
135 were transported to the storage tank 140 or directly to the closed second reactor
150. The temperature of the closed second reactor 150 (capacity: 1 m!) was maintained
at 450°C. The second reactor 150 was rotated for 30 rrin at a speed of 3 rpm while
injecting oxygen gas at the pressure of 2 Kgf/cm . Samples of the reactant were
collected at 5,10, 20, and 30 min after starting (he reaction. The contents of un-reacted
bismuth in the collected samples were measured to check reaction rates, and the result
is shown in Table 2.
Example 4
The same method as Example 3 was performed except that reaction product obtained
from the first reactor 120 at the reaction temperature of 500°C and containing 0.87%
un-feacted bismuth according to Example 2 was used. The contents of un-reacted
bismuth in collected samples were measured to check reaction rates, and the result is
shown in Table 2.
Example 5
The same method as Example 3 was performed except that reaction product obtained
from the first reactor 120 at the reaction temperature of 450°C and containing 2.8% un-
reacted bismuth according to Example 2 was used. The contents of un-reacted bismuth
in collected samples were measured to check reaction rates, and the result is shown in
Table 2.
Example 6
The same method as Example 3 was performed except that reaction product obtained
frcm the first reactor 120 at the reaction temperature of 500oC and containing 8.4% un-
reacted bismuth according to Example 1 was used. The contents of un-reacted bismuth

in collected samples were measured to check reaction rates, and the result is shown in
Table 2.
Comparative Examples 1-4
Comparative Examples 1 - 4 were prepared in the same methods as Examples 3-6
respectively except that oxygen gas was not injected. The contents of un-reacted
bismuth in collected samples were measured to check reaction rates, and the result is
shown in Table 2.

Table 2 shows un-reacted bismuth contents (%) corresponding to the elapsed reaction

time in the condition of stirring the closed second reactor 150 where the secondary
oxidation occurs with supply of oxygen gas at the pressure of 2 Kgf/cm2 and in the
condition of stirring in a closed state without supply of oxygen gas. All the un-reacted
bismuth contents after the secondary oxidation with oxygen injection show 0.005%. In
contrast, un-reacted bismuth contents after the secondary oxidation without oxygen
injection (Comparative Examples 3 - 4) show much higher percentages.
Example 7
The same method as Example 3 was performed except that reaction product obtained
frcm the first reactor 120 at the reaction temperature of 650°C and containing 0.04%
un-reacted bismuth according to Example 2 was supplied to the second reactor 150
while maintaining the temperature at 500°C and oxygen gas was injected for 20 min at
the pressures of 1 Kgf/cm2 and 2.5 Kgf/cm2. The contents of un-reacted bismuth in
collected samples were measured to check reaction rates, and the result is shown in
Table 3.

Referring to Table 3, it is identified that the oxidation rate in the second reactor
depends on a feeding rate of oxygen.)
Example 8
To test an oxidation efficiency in the second reactor 150, reaction product obtained
from the first reactor 120 at reaction temperature of 500°C and containing 0.87% un-
reacted bismuth according to Example 2 was continuously supplied to the second
reactor 150 and oxidized for 20 min by. supplying oxygen gas at the pressure of 2 Kgf/
cm2 and by changing the reaction temperature to 300, 400,450,500, 550, and 600°C.
The contents of un-reacted bismuth in collected samples were measured to check
reaction rates, and the result is shown in Table 4.
Table 4


Referring to Table 4, the reaction temperature of the second reactor 150 is preferably
400 - 600°C, and more preferably 450 - 600°C when considering economical
efficiency.
Comparative Example 5
The same method as Example 1 was performed for 8 hours a day except that hot air
is not supplied. Scale formed on the inner wall of the first reactor 120 was measured
after 7, 15, and 30 days. The result is shown in Table 5.

As shown in Table 5, in the case that hot air is not injected, scale was formed sig-
nificantly after 7 days, and after 15 days, the first reactor 120 reached a state that it can
be operated no longer without cleaning the scale. In the case that hot air is supplied,
the thickness of scale was only 11 rrm after 30 days. Therefore, if hot air is supplied.

the reaction system may operate efficiently by cleaning the scale deposited in the inner
wall of the first reactor once a month..
Experimental Example 1
An X-ray diffraction (XRD) was used to identify a crystal structure of bisrmuth oxide
obtained in the above examples.
α-bismuth oxide (Aldrich, Purity 99.999%) was ased as a reference material.
Sample 1 was prepared in a condition that melted bismuth was supplied to an open
first reactor at a reaction temperature of 450°C and at a feeding rate of 40 Kg/hr while
maintaining suction floating pressure at 15rrm H2O and stirring with an impeller.
Sample 2 was prepared in a condition that melted bisrmuth was supplied to the open
first reactor at a reaction temperature of 500°C and at a feeding rate of 40 Kg/hr while
maintaining suction floating pressure at 15mm H2O and stirring with the impeller.
Sample 3 was prepared in a condition that melted bismuth was supplied to the first
reactor at a reaction temperature of 550°C and at a feeding rate of 20 Kg/hr while
maintaining suction floating pressure at 10mri H2O and stirring with the impeller.

Sample 4 was prepared in a condition that melted bismuth was supplied to the first
reactor at a reaction temperature of 450°C and at the feeding rate of 40 Kg/hr while
maintaining suction floating pressure at 15mm H2 O and stirring with the impeller, and

then the primarily oxidized bismuth was oxidized in a second reactor at 500°C while
supplying oxygen gas at the pressure 1 Kgf/cm.
The above samples and the reference material of abismuth oxide were measured by
an X-ray diffraction, and the result is shown in FIG. 4. All the above samples showed
the same peak points as those of the reference material.
Experimental Example 2
The same method as preparing sample 4 in Experimental Example 1 was performed
except that the reaction temperature of the second reactor was maintained at 450°C.
Collected samples were measured by the X-ray diffraction in the same method as Ex-
perimental Example 1, arid the result is shown in FIG. 5.
According to Experimental Examples 1 and 2, all the bismuth oxides prepared
according to the exemplary embodiment of the present invention were identified to be
an α-type.

We claim:-
1. A method of preparing bismuth oxide comprising :
melting bismuth metal;
transporting the melted bismuth metal to an open first reactor and oxidizing
the melted bismuth metal at a temperature of 300-650 °C while stirring; and
transporting bismuth oxide and un-reacted material to a closed second
reactor through a screw and oxidizing the bismuth oxide and un-reacted
material while rotating the second reactor at a temperature of 300-600 °C
with a supply of air or oxygen.
2. The method of preparing bismuth oxide as claimed in claim 1, wherein the
bismuth metal is melted at the temperature of 300-450 °C.
3. The method of preparing bismuth oxide as claimed in claim 1, wherein the
bismuth metal is melted at the temperature of 400-450 °C.
4. The method of preparing bismuth oxide as claimed in claim 1, wherein
oxidation is executed in the first reactor at the temperature of 400-600 °C.
5. The method of preparing bismuth oxide as claimed in claim 1, wherein
oxidation is executed in the second reactor at the temperature of 400-600 °C.
6. The method of preparing bismuth oxide as claimed in claim 1, wherein hot
air of 200-450 °C is supplied into the first reactor.
7. The method of preparing bismuth oxide as claimed in claim 6, wherein hot
air of 300-450 °C is supplied into the first reactor.
8. The method of preparing bismuth oxide as claimed in claim 1, wherein
bismuth oxide is collected by an exhaust fan installed in a collecting device
while maintaining the pressure inside the collecting device at 10-30 mm
H2O.
9. The method of preparing bismuth oxide as claimed in claim 1, wherein the
air or oxygen is injected into the second reactor at a pressure of 1-2.5
Kgf/cm2.
10. An apparatus for preparing bismuth oxide comprising :
a melting tank (110) for melting bismuth metal at a high temperature;

a first reactor (120) having an internal rotating impeller (121) for primary
oxidation of the melted bismuth metal;
a collecting device (130) having an exhaust fan (134) for collecting bismuth
oxide formed in the first reactor (120) by differential pressure; and
a closed second reactor (150) and an oxygen inlet for secondary oxidation of
bismuth oxide collected by the collecting device (130).
11. The apparatus for preparing bismuth oxide as claimed in claim 10,
further comprising a pulverizer (160) for pulverizing bismuth oxide
exhausted from the second reactor (150).
12. The apparatus for preparing bismuth oxide as claimed in claim 10,
further comprising an injection pipe (122) for supplying air or oxygen into
the first reactor (120).
13. The apparatus for preparing bismuth oxide as claimed in claim 12,
wherein the injection pipe (122) is formed in the axis of an impeller (121).
14. The apparatus for preparing bismuth oxide as claimed in claim 10,
wherein the collecting device (130) comprises :
a settling tank (131) for stabilizing bismuth oxide supplied from the first
reactor (120);
a cyclone (132) for circulating air flow to be sucked by an exhaust fan (134);
and
a collecting tank (133) having the exhaust fan (134) for collecting the
bismuth oxide.



Abstract


PROCESS FOR PREPARING BISMUTH OXIDE, AND THE
APPARATUS THEREFOR
A method of preparing bismuth oxide and an apparatus therefor are
disclosed. The method includes: melting metal bismuth, transporting the melted
metal bismuth to an open first reactor and oxidizing the melted metal bismuth
while stirring at the temperature of 300-650°C and transporting bismuth oxide
and un-reactd material to an closed second reactor through a screw and
oxidizing the bismuth oxide and an un-reacted material while rotating the closed
second reactor at the temperature of 300-600°C with supply of air oxygen.

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3248-KOLNP-2009-PCT IPER.pdf

3248-kolnp-2009-PETITION UNDER RULE 8.pdf

3248-KOLNP-2009-PRIORITY DOCUMENT.pdf

3248-kolnp-2009-REPLY TO EXAMINATION REPORT.pdf

3248-kolnp-2009-specification.pdf

3248-KOLNP-2009-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

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Patent Number 258674
Indian Patent Application Number 3248/KOLNP/2009
PG Journal Number 05/2014
Publication Date 31-Jan-2014
Grant Date 30-Jan-2014
Date of Filing 14-Sep-2009
Name of Patentee DANSUK INDUSTRIAL CO., LTD.
Applicant Address 705, 1DA SHIHWA INDUSTRIAL COMPLEX, 1239-5, JEONGWANG 2(i)- DONG, SIHEUNG-SI, GYEONGGI-DO 429-452, KOREA
Inventors:
# Inventor's Name Inventor's Address
1 KIM, DONG-EON 2014-1202, SEOHAE APT., CHOJI-DONG, DANWON-GU, ANSAN-SI, GYEONGGI-DO 425-080, KOREA
2 HAN, SEUNG-WOK B-1705 HYUNDAI SUPERVILL, 1441-11, SEOCHO-DONG, SEOCHO-GU, SEOUL 137-070, KOREA
3 LIM, BYUNG-GIL 203-1206, JUGONG MIRAE TOWN APT., SAMSAN-DONG, BUPYEONG-GU, INCHEON 403-090 KOREA
PCT International Classification Number C01G29/00; C01G29/00
PCT International Application Number PCT/KR2007/003538
PCT International Filing date 2007-07-23
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2007-40222 2007-04-25 Republic of Korea