CA1043982A - Process for the manufacture of fine particle size metal oxides - Google Patents
Process for the manufacture of fine particle size metal oxidesInfo
- Publication number
- CA1043982A CA1043982A CA214,598A CA214598A CA1043982A CA 1043982 A CA1043982 A CA 1043982A CA 214598 A CA214598 A CA 214598A CA 1043982 A CA1043982 A CA 1043982A
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- gases
- titanium
- reaction
- metal
- reaction product
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/07—Producing by vapour phase processes, e.g. halide oxidation
- C01G23/075—Evacuation and cooling of the gaseous suspension containing the oxide; Desacidification and elimination of gases occluded in the separated oxide
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
- C01G23/04—Oxides; Hydroxides
- C01G23/047—Titanium dioxide
- C01G23/07—Producing by vapour phase processes, e.g. halide oxidation
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
PROCESS FOR THE MANUFACTURE OF FINE
PARTICLE SIZE METAL OXIDES
ABSTRACT OF INVENTION
Metal oxides are prepared by reacting the corresponding gaseous metal chloride with oxygen, or oxygen-containing gas, at elevated temperature to form metal oxide-burdened reaction gases at elevated pressure, the metal oxide-burdened reaction gases being thereafter conducted into and through successive gas cooling and metal oxide separating zones, respectively, and feeding the metal oxide-free gases, while still at elevated pressure, into a chlorinating zone to chlorinate a metal bearing ore and form additional gaseous metal chloride.
PARTICLE SIZE METAL OXIDES
ABSTRACT OF INVENTION
Metal oxides are prepared by reacting the corresponding gaseous metal chloride with oxygen, or oxygen-containing gas, at elevated temperature to form metal oxide-burdened reaction gases at elevated pressure, the metal oxide-burdened reaction gases being thereafter conducted into and through successive gas cooling and metal oxide separating zones, respectively, and feeding the metal oxide-free gases, while still at elevated pressure, into a chlorinating zone to chlorinate a metal bearing ore and form additional gaseous metal chloride.
Description
11` BACKGr~OUND OF INVEN'TION
121 The prod-lction of fine particle size metal oxides by 13,~ reactin~, at high temperature, the corresponding gaseous metal 14¦ chloride .ith oxygen or a oxygen-containin~ gas, either mixed 151jwith the metal chloride or introduced separately into a reaction 16 li chamber, is well known. The process is sometimes referred to 17,lin the art as the vapor phase oxidation process.
18~ In order to obtain the required high temperatures 19', for the reaction to go to substantial completion it is necessary that at least one of the two reactants, i.e. the metal chloride ~,or o~ygen, be heated prior to introduction into the reaction 22 ¦, chamber; and/or an additional gaseous component be added whicll ~3 l, is either heated to a high temperature prior to being introduced 24 ~l into the reaction chamber, or is burned wit~in the reaction chambe 25 ,, so as to provide the necessary hi~ reaction temperatures in the 26l'reactor. In some processes the reaction is effected in an empty 27 1, reaction cha~her while in ~thers, the reaction is carried out in 28 " a fluidi~ed bed of coarse particles such as, for exam~le, coarse j, 29 ' titanium dioxide. The reaction products comprise finely dividecl 30 ! n?etal o~ide suspended in the reaction gases l~hich include ~a,seous 4~
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chlorine. These gases are at temperatures of the order of 1000C or higher and must be cooled before separating the finely divided metal oxide therefrom. Cooling the reaction product gases is fre~uently carried out by adding a recycled cold gas to the gases, and/or indirectly by conducting the reaction product gases through a heat exchanger. Separation of the finely divided metal oxide from the cooled gases is then effected by a filter, cyclone or equivalent device.
As mentioned at the outset the vapor phase oxidation process for producing metal oxides requires the use of gaseous metal chlorides. In general, these metal chlorides are produced by passing gaseous chlorine together with oxygen, and carbon dioxide through a mixture of finely divided ore and carbon at elevated temperatures to remove the metal from the ore as a gaseous metal chloride. In the development of the vapor phase oxidation process it was early appreciated that the reaction product gases, freed - of the finely divided metal oxide, comprised significant amounts of chlorine, carbon dioxide and oxygen which gaseous mixture could be used in the chlorination of metal bearing ores for producing metal chlorides. However, inasmuch as chlorination of the ore is generally carried out at pressures of from 4 to 14 psig, it has heretofore been the practice to cool the reaction product gases and then compress the cooled gases using suitable compressors for feeding the gases into the chlorinator, all as more fully disclosed in U.S. Patent No. 3,560,152 Dunham, Jr. et al.
This practice has, however, encountered serious difficulties due to the fact that these compressed gases contain small percentages of unreacted titanium tetrachloride - a -. . .
gL0~3~
and ~2SO4 mist react to form crust-like materials within the compressors resulting in frequent malfunctioning and/or breakdown of the compressors. It becomes absolutely necessary, therefore, to remove these materials from the gases before the gases are compressed.
t has been suggested in German published applica-tion 1817347 that the gases be washed at a temperature not exceeding 50C using concentrated sulfuric acid; that the washed gases be subsequently compressed, using a liquid piston compressor with concentrated sulfuric acid as the working liquid; and that thereafter the gases be passed through a suitable separator in order to remove any residual solid material and sulfuric acid from the gases. This procedure has definite disadvantages, however, in that the ; substances removed by washing contain sulfate values which are thereby lost to the process. In addition, the viscosity of the sulfuric acid is increased by the presence of sulfate values so that the sulfuric acid becomes difficult to handle and must be replaced frequently by fresh acid.
Moreover, the compressed gas, which has been cooled, must be reheated prior to its introduction into the chlorinator;
or alternatively it is necessary to burn additional fuel in the chlorinator in order to maintain chlorination tempera-tures, and further, the equipment required for cooling the reaction product gases, for washing the cooled gases and for subsequently compressing the gases separating the residue, and reheating the gases is complicated and, as a consequence, many operational difficulties are encountered.
Further, the equipment is prone to malfunctioning with high attendant repair cost.
~ _ 3 _ 1~39~'~
SUMMARY OF Tl-IE INVENTION
, _ The present invention is the discovery of an improved vapor phase oxidation process for the production of fine particle ~ 3a -: .- - - .
~O ~ 3 ~
size oxides of metals whose chlorides are easily volatile, which process does not exhibit the above mentioned dis-advantages. Thus, the process of this invention comprises the steps of feeding preheated gaseous titanium tetra-chloride and oxygen into a heated reaction zone and reacting said titanium tetrachloride and oxygen at elevated pressure and a temperature of at least 1000C. to form titanium dioxide suspended in the reaction product gases, including gaseous chlorine, conducting the titanuum oxide - burdened reaction product gases from the reaction zone into and through successive cooling and titanium dioxide separating zones, respectively, to cool the reaction product gases down to 200 - 400~C., the pressure of the gases in said reaction zone being in the range of 12-20 psig, such that the titanium dioxide free gases exiting from said separation zones are recycled without further compression into a chlorination zone to chlorinate said titanium bearing ore and form additional titanium tetrachloride.
A significant advantage of the process of this in-vention is seen in the fact that the pressure in the reaction or oxidation chamber is sufficient to convey the reaction products, i.e. solid particulate metal oxide and gases, through successive cooling and separation zones and to carry the solids-free gases into the chlorinator without the need for supplementary compression. Thus the only place where pressure is generated is where the reactants are introduced into the oxidation chamber. Another advantage of the instant invention is that inasmuch as the gases are handled~at high pressures the separa*or or filter means is capable of handling much higher loads of oxides than in known processes and as a consequence separators may be constructed on a smaller scale ` ~ _ 4 _ ~ 043~
at equal throughput or, alternatively, the throughput may be increased with the same size separator. The same holds true for the reaction chamber and the cooling means. Further, with the elimination of gas compressors it is not necessary that the gases, freed of oxides, be washed with sulfuric acid and subjected to further purification. Consequently, losses of non-reacted chlorides and oxychlorides are avoid-ed. In fact, these components may be carried along through the entire - 4a -.
, ~: ~043~
~ ' .
1 svstem from the re~ctor into t~c chlorinator. ~!orcover for the
121 The prod-lction of fine particle size metal oxides by 13,~ reactin~, at high temperature, the corresponding gaseous metal 14¦ chloride .ith oxygen or a oxygen-containin~ gas, either mixed 151jwith the metal chloride or introduced separately into a reaction 16 li chamber, is well known. The process is sometimes referred to 17,lin the art as the vapor phase oxidation process.
18~ In order to obtain the required high temperatures 19', for the reaction to go to substantial completion it is necessary that at least one of the two reactants, i.e. the metal chloride ~,or o~ygen, be heated prior to introduction into the reaction 22 ¦, chamber; and/or an additional gaseous component be added whicll ~3 l, is either heated to a high temperature prior to being introduced 24 ~l into the reaction chamber, or is burned wit~in the reaction chambe 25 ,, so as to provide the necessary hi~ reaction temperatures in the 26l'reactor. In some processes the reaction is effected in an empty 27 1, reaction cha~her while in ~thers, the reaction is carried out in 28 " a fluidi~ed bed of coarse particles such as, for exam~le, coarse j, 29 ' titanium dioxide. The reaction products comprise finely dividecl 30 ! n?etal o~ide suspended in the reaction gases l~hich include ~a,seous 4~
! ' .
~= ~ ... . .
'`. : '' , ' ~ ,' .~ ':
- , ~
',: ' ' ' - :
: ' : ' ' .:: , '~ . . ' ', : : : , '.' .. '' : ' ' ~ ' ' ' ' . ,, ~ ' ',' "
.' .-. ' , - ' " , ~- :
~ 39~
chlorine. These gases are at temperatures of the order of 1000C or higher and must be cooled before separating the finely divided metal oxide therefrom. Cooling the reaction product gases is fre~uently carried out by adding a recycled cold gas to the gases, and/or indirectly by conducting the reaction product gases through a heat exchanger. Separation of the finely divided metal oxide from the cooled gases is then effected by a filter, cyclone or equivalent device.
As mentioned at the outset the vapor phase oxidation process for producing metal oxides requires the use of gaseous metal chlorides. In general, these metal chlorides are produced by passing gaseous chlorine together with oxygen, and carbon dioxide through a mixture of finely divided ore and carbon at elevated temperatures to remove the metal from the ore as a gaseous metal chloride. In the development of the vapor phase oxidation process it was early appreciated that the reaction product gases, freed - of the finely divided metal oxide, comprised significant amounts of chlorine, carbon dioxide and oxygen which gaseous mixture could be used in the chlorination of metal bearing ores for producing metal chlorides. However, inasmuch as chlorination of the ore is generally carried out at pressures of from 4 to 14 psig, it has heretofore been the practice to cool the reaction product gases and then compress the cooled gases using suitable compressors for feeding the gases into the chlorinator, all as more fully disclosed in U.S. Patent No. 3,560,152 Dunham, Jr. et al.
This practice has, however, encountered serious difficulties due to the fact that these compressed gases contain small percentages of unreacted titanium tetrachloride - a -. . .
gL0~3~
and ~2SO4 mist react to form crust-like materials within the compressors resulting in frequent malfunctioning and/or breakdown of the compressors. It becomes absolutely necessary, therefore, to remove these materials from the gases before the gases are compressed.
t has been suggested in German published applica-tion 1817347 that the gases be washed at a temperature not exceeding 50C using concentrated sulfuric acid; that the washed gases be subsequently compressed, using a liquid piston compressor with concentrated sulfuric acid as the working liquid; and that thereafter the gases be passed through a suitable separator in order to remove any residual solid material and sulfuric acid from the gases. This procedure has definite disadvantages, however, in that the ; substances removed by washing contain sulfate values which are thereby lost to the process. In addition, the viscosity of the sulfuric acid is increased by the presence of sulfate values so that the sulfuric acid becomes difficult to handle and must be replaced frequently by fresh acid.
Moreover, the compressed gas, which has been cooled, must be reheated prior to its introduction into the chlorinator;
or alternatively it is necessary to burn additional fuel in the chlorinator in order to maintain chlorination tempera-tures, and further, the equipment required for cooling the reaction product gases, for washing the cooled gases and for subsequently compressing the gases separating the residue, and reheating the gases is complicated and, as a consequence, many operational difficulties are encountered.
Further, the equipment is prone to malfunctioning with high attendant repair cost.
~ _ 3 _ 1~39~'~
SUMMARY OF Tl-IE INVENTION
, _ The present invention is the discovery of an improved vapor phase oxidation process for the production of fine particle ~ 3a -: .- - - .
~O ~ 3 ~
size oxides of metals whose chlorides are easily volatile, which process does not exhibit the above mentioned dis-advantages. Thus, the process of this invention comprises the steps of feeding preheated gaseous titanium tetra-chloride and oxygen into a heated reaction zone and reacting said titanium tetrachloride and oxygen at elevated pressure and a temperature of at least 1000C. to form titanium dioxide suspended in the reaction product gases, including gaseous chlorine, conducting the titanuum oxide - burdened reaction product gases from the reaction zone into and through successive cooling and titanium dioxide separating zones, respectively, to cool the reaction product gases down to 200 - 400~C., the pressure of the gases in said reaction zone being in the range of 12-20 psig, such that the titanium dioxide free gases exiting from said separation zones are recycled without further compression into a chlorination zone to chlorinate said titanium bearing ore and form additional titanium tetrachloride.
A significant advantage of the process of this in-vention is seen in the fact that the pressure in the reaction or oxidation chamber is sufficient to convey the reaction products, i.e. solid particulate metal oxide and gases, through successive cooling and separation zones and to carry the solids-free gases into the chlorinator without the need for supplementary compression. Thus the only place where pressure is generated is where the reactants are introduced into the oxidation chamber. Another advantage of the instant invention is that inasmuch as the gases are handled~at high pressures the separa*or or filter means is capable of handling much higher loads of oxides than in known processes and as a consequence separators may be constructed on a smaller scale ` ~ _ 4 _ ~ 043~
at equal throughput or, alternatively, the throughput may be increased with the same size separator. The same holds true for the reaction chamber and the cooling means. Further, with the elimination of gas compressors it is not necessary that the gases, freed of oxides, be washed with sulfuric acid and subjected to further purification. Consequently, losses of non-reacted chlorides and oxychlorides are avoid-ed. In fact, these components may be carried along through the entire - 4a -.
, ~: ~043~
~ ' .
1 svstem from the re~ctor into t~c chlorinator. ~!orcover for the
2 l~tter reason oxidation o-f the metal chloricles may he incompl~te~ ¦
3~ i.e. an a~reciable portion of the metal chlorides need not be
4' reacted. 1~1hile heretofore oxiclatlon of the metal chlori~es had 5l to be carried out at temperatures as high as possible in order to 6 li obtain substantially complete conversion of the metal chlorides 71~ to metal oxides, it is now possible, using the process according 8 ! to the instant invention, to operate at lower temperatures.
9 I Thus~ on the one hand, energy for preheating the reactants may be 10 I saved and, on the other hand, the cooling means for cooling the 11 I reaction product gases, including suspended particulate metal 12 1 oxide, may be smaller andlor of simpler construction than in 13ll known processes. Moreover, if combustible ~uxiliary gases are 14 ll employed or generating auxiliary heat then the amount needed 15 ¦l is less than that required in knol~n processes; and in fact, the 16j, auxiliary gases may be omitted entirely. Further, since no 17l' compressors are needed for pressurizing the gases, it is not 18~lnecessary to cool the gases to a temperature lower than is 19~ absolutely necessary for subsenuent removal of the metal oxides.
201 ~lence, it is possible to introduce the gases into~the chlorinator 21 ¦, at a hi~her temperature than previously thus reducing fuel 22 ¦i consumption in the chlorinator.
2311 .
24 ~j DESCRIPTION OF DRAI~ING
25 ll The dral~in~ is a flow diagram of the system of this 26~'invention for producing a metal oxide by vapor phase oxidation 27 1i of the corresponding metal chloride.
28 ,l 29 .
30 ' , 5 ' .,.' , .. . . . .
3'36~
PREFERRED EMBODIMENT OF INVENTION
Pursuant to the discovery of the present invention, - a preferred embodiment is illustrated schematically in the drawing and comprises essentially, a reaction or oxidation zone 10, in which preheated metal chloride and oxygen, or an oxygen-containing gas, are reac:ted at elevated temperat-ures with or without the use of an auxiliary fuel which may be a liquid, a solid, or a gaseous fuel, such as, for example, carbon monoxide; a cooling zone 11 preferably in the form of indirect cooling means such as a water-cooled tubular chamber; a separating zone 12 which may be in the form of a bag filter of the type described in the a~ore-said U.S. Patent 3,560,152; and a chlorination zone 13 comprising a chlorinator such as for example the chlorinator described in U.S. 3,101,249; the reaction zone, cooling zone, separating zone and chlorination zone being connected in a manner such that the pressurized reaction product gases formed in the reaction zone will carry through into and through the cooling zone and separating zone respectively, and as a consequence may be fed directly into the chlorinator without requiring a gas compressor or equivalent device.
The entire system including the reaction chamber, cooling means, separating means and chlorinator is of relatively simple construction and as a consequence the process can be easily controlled.
The pressure of the reaction gases within the reaction chamber must be sufficiently high that the gases will flow without the aid of compressors, from the reaction chamber to and through the cooling and separating zones 3a and into the chlorinator. As practiced in the art, ~ - 6 -:~4;~
chlorinators designed to produce metal chlorides usually operate at pressures of from about 4 to 14 psig. The pressure losses expected in the cooling zone and in the separator or filter will depend on large measures on the size of - 6a -~0 ~ 3 9 ~ ~
1 the e~ui~1nent~ through~ut of materials an(l related reaction 2 cond:itions ~y ~ray o illustration only, the accumulated press-lre 31,losses exl~ected in ~he cooling zone and Eilter for a system ,joperatinc~ at an oxygen feed rate of ahout 96 standard cubic meters , , .
9 I Thus~ on the one hand, energy for preheating the reactants may be 10 I saved and, on the other hand, the cooling means for cooling the 11 I reaction product gases, including suspended particulate metal 12 1 oxide, may be smaller andlor of simpler construction than in 13ll known processes. Moreover, if combustible ~uxiliary gases are 14 ll employed or generating auxiliary heat then the amount needed 15 ¦l is less than that required in knol~n processes; and in fact, the 16j, auxiliary gases may be omitted entirely. Further, since no 17l' compressors are needed for pressurizing the gases, it is not 18~lnecessary to cool the gases to a temperature lower than is 19~ absolutely necessary for subsenuent removal of the metal oxides.
201 ~lence, it is possible to introduce the gases into~the chlorinator 21 ¦, at a hi~her temperature than previously thus reducing fuel 22 ¦i consumption in the chlorinator.
2311 .
24 ~j DESCRIPTION OF DRAI~ING
25 ll The dral~in~ is a flow diagram of the system of this 26~'invention for producing a metal oxide by vapor phase oxidation 27 1i of the corresponding metal chloride.
28 ,l 29 .
30 ' , 5 ' .,.' , .. . . . .
3'36~
PREFERRED EMBODIMENT OF INVENTION
Pursuant to the discovery of the present invention, - a preferred embodiment is illustrated schematically in the drawing and comprises essentially, a reaction or oxidation zone 10, in which preheated metal chloride and oxygen, or an oxygen-containing gas, are reac:ted at elevated temperat-ures with or without the use of an auxiliary fuel which may be a liquid, a solid, or a gaseous fuel, such as, for example, carbon monoxide; a cooling zone 11 preferably in the form of indirect cooling means such as a water-cooled tubular chamber; a separating zone 12 which may be in the form of a bag filter of the type described in the a~ore-said U.S. Patent 3,560,152; and a chlorination zone 13 comprising a chlorinator such as for example the chlorinator described in U.S. 3,101,249; the reaction zone, cooling zone, separating zone and chlorination zone being connected in a manner such that the pressurized reaction product gases formed in the reaction zone will carry through into and through the cooling zone and separating zone respectively, and as a consequence may be fed directly into the chlorinator without requiring a gas compressor or equivalent device.
The entire system including the reaction chamber, cooling means, separating means and chlorinator is of relatively simple construction and as a consequence the process can be easily controlled.
The pressure of the reaction gases within the reaction chamber must be sufficiently high that the gases will flow without the aid of compressors, from the reaction chamber to and through the cooling and separating zones 3a and into the chlorinator. As practiced in the art, ~ - 6 -:~4;~
chlorinators designed to produce metal chlorides usually operate at pressures of from about 4 to 14 psig. The pressure losses expected in the cooling zone and in the separator or filter will depend on large measures on the size of - 6a -~0 ~ 3 9 ~ ~
1 the e~ui~1nent~ through~ut of materials an(l related reaction 2 cond:itions ~y ~ray o illustration only, the accumulated press-lre 31,losses exl~ected in ~he cooling zone and Eilter for a system ,joperatinc~ at an oxygen feed rate of ahout 96 standard cubic meters , , .
5 1I per hour and a titanium tetrachloride feed rate of about 5no
6 1l kilograms per hour is about 3 psi. As a consequence, when using
7 la system of approximately this ca~acity the reaction product
8 ¦gases generated in the reaction chamher should ~e at a pressure
9 of at least about 12 psig or higher ~ut not higher than about 20 psig.
11 The reactants i.e. gaseous titanium tetrachloride and 12 oxy~en must be introduced into the reaction chamber under pressllre 13 higher than the cumulative pressure developed within the reaction 14 ~chamber as a result o the increase in temperature during combus-15 Ition oE the gases and the backpressure created in the system 16 jdue to the pressure in the chlorinator plus riction of the gases ion the ~all of the conduits passing through the filter means, etc.
18 illence, because o the complexity of t}lese factors it is impractical 19 Ito ~ive specific values to the pressures at ~rhich the reactants 20 lare introduced into the reaction chanber.
21 ~ itll regard to cooling the reaction product C~ases 22 ~leavin~ the reaction chamber it is prefcrred to cool the reaction ~-23 ¦~product gases hy indirect cooling, as for e~am~le, by a ~Yater-24 l¦cooled heat exchanger in the form of a length of tuhin~ ~rovided with a muffle or jacket through which a coolant such as ~ater is ,circulated. ~ue to the gas pressure nrevailing in the tuling or j duct an increased heat transer is secured. Furthermpre, ~rhile heretoFore it has heen the ~ra~tice to partially cool the reaction l~l?ro~uct gases hy contacting them ~ith relatively cold recycled 3 g~ases~ this co~t?le~ and e~pensive aspect of the overall process l - 7 -- . - . ., : ;
:: . ' . . . --. - . ~ , ~LO~;~9~ i l is no longer neccssary.
2 Thus, an important caturc of the present invention 3' consists in coolin~ the pressurizetl reaction product gases Erom 4 reaction temneratures, i.e. above 1()00C down to 200-400C~ ¦
5!lthereafter separating the sus~ended metal oxide Erom the cooled 6 Il gases and. ~rithout further cooling or employment of compressors, 7l conducting the gases directly into a chlorinator in ~hich, by 8 ¦reaction with an ore or other oxidic material, the metal chloride 91lis ormed. Chlorine and any unreacted metal chloride ~n the lolireaction product gases may be recycled without encountering losses or creating ~alfunctioning o the system.
12¦l As mentioned supra, after the reaction product gases 31~have been cooled in the cooling zone the finely divided metal 14j¦oxide can be removed rom thcse gases in a manner knol~rn as such 15 'as for ~xample, by ashing l~it~ a liquid; it is hol~ever, 16!lparticularly advantageQus to effect separation o the oxide from - 17l the gases in the dry ~Yay, as for example, by use of a suitable 18!lfilter of the type referred to supra and/or by means of a cyclone.
l9i~Owing to the pressure of the reaction product gases concentration 20,iof the suspended metal oxide in the gases is increased thus ` 21l resulting in an increase in agglomerates ~7hich rnay be separated A~ 22 1l relatively easily from the gases. Conse~uently, the separator mea s 23 l'may be smaller ~hile maintaining t~e same separation output as 24 ¦ in kno~rn processes, or if the separator means is of equal size thel 25 ¦I the rate o separation of the oxide from the gases will be greater.
26 I Furthermore, the pressure loss in the sep~r~tor l~7ill be slight i 27 l SUC]I that tlle residual pressure of the oxicle-free gases ~`Jill he 28 i sufficient to transport the gases. ~rithotlt rene~.~ed compression 9 29 l into tlle chlorinator. 'loreover, by selecting suitable filter 3 material such as for ecample, ~roven metal filter 7n~s or similar `,..... ' I
: ' ' ' .
1O~;~9~,L, 1 ~all material Eor a cyclone, sc~aratio~ oF the oxit~c from t}!e 2 gascs may take placc at rc]~tivc:ly high tel~peratllres as a 3I consenuencc of ~-rhicll relleating oE the ~ases is unnecessarv and 4I hence energry is saved in clllorination~ And further, ~rhen separa-51¦ tion of the metal oxicle from the reaction product gases is done 6~ by dry separation the solids-free gases are free from contaminatior 7 by liquid or liquid vapors~ and there will be no loss of unreacted 8 chloride values by washing.
- 9 The invention is particularly adapted to the production
11 The reactants i.e. gaseous titanium tetrachloride and 12 oxy~en must be introduced into the reaction chamber under pressllre 13 higher than the cumulative pressure developed within the reaction 14 ~chamber as a result o the increase in temperature during combus-15 Ition oE the gases and the backpressure created in the system 16 jdue to the pressure in the chlorinator plus riction of the gases ion the ~all of the conduits passing through the filter means, etc.
18 illence, because o the complexity of t}lese factors it is impractical 19 Ito ~ive specific values to the pressures at ~rhich the reactants 20 lare introduced into the reaction chanber.
21 ~ itll regard to cooling the reaction product C~ases 22 ~leavin~ the reaction chamber it is prefcrred to cool the reaction ~-23 ¦~product gases hy indirect cooling, as for e~am~le, by a ~Yater-24 l¦cooled heat exchanger in the form of a length of tuhin~ ~rovided with a muffle or jacket through which a coolant such as ~ater is ,circulated. ~ue to the gas pressure nrevailing in the tuling or j duct an increased heat transer is secured. Furthermpre, ~rhile heretoFore it has heen the ~ra~tice to partially cool the reaction l~l?ro~uct gases hy contacting them ~ith relatively cold recycled 3 g~ases~ this co~t?le~ and e~pensive aspect of the overall process l - 7 -- . - . ., : ;
:: . ' . . . --. - . ~ , ~LO~;~9~ i l is no longer neccssary.
2 Thus, an important caturc of the present invention 3' consists in coolin~ the pressurizetl reaction product gases Erom 4 reaction temneratures, i.e. above 1()00C down to 200-400C~ ¦
5!lthereafter separating the sus~ended metal oxide Erom the cooled 6 Il gases and. ~rithout further cooling or employment of compressors, 7l conducting the gases directly into a chlorinator in ~hich, by 8 ¦reaction with an ore or other oxidic material, the metal chloride 91lis ormed. Chlorine and any unreacted metal chloride ~n the lolireaction product gases may be recycled without encountering losses or creating ~alfunctioning o the system.
12¦l As mentioned supra, after the reaction product gases 31~have been cooled in the cooling zone the finely divided metal 14j¦oxide can be removed rom thcse gases in a manner knol~rn as such 15 'as for ~xample, by ashing l~it~ a liquid; it is hol~ever, 16!lparticularly advantageQus to effect separation o the oxide from - 17l the gases in the dry ~Yay, as for example, by use of a suitable 18!lfilter of the type referred to supra and/or by means of a cyclone.
l9i~Owing to the pressure of the reaction product gases concentration 20,iof the suspended metal oxide in the gases is increased thus ` 21l resulting in an increase in agglomerates ~7hich rnay be separated A~ 22 1l relatively easily from the gases. Conse~uently, the separator mea s 23 l'may be smaller ~hile maintaining t~e same separation output as 24 ¦ in kno~rn processes, or if the separator means is of equal size thel 25 ¦I the rate o separation of the oxide from the gases will be greater.
26 I Furthermore, the pressure loss in the sep~r~tor l~7ill be slight i 27 l SUC]I that tlle residual pressure of the oxicle-free gases ~`Jill he 28 i sufficient to transport the gases. ~rithotlt rene~.~ed compression 9 29 l into tlle chlorinator. 'loreover, by selecting suitable filter 3 material such as for ecample, ~roven metal filter 7n~s or similar `,..... ' I
: ' ' ' .
1O~;~9~,L, 1 ~all material Eor a cyclone, sc~aratio~ oF the oxit~c from t}!e 2 gascs may take placc at rc]~tivc:ly high tel~peratllres as a 3I consenuencc of ~-rhicll relleating oE the ~ases is unnecessarv and 4I hence energry is saved in clllorination~ And further, ~rhen separa-51¦ tion of the metal oxicle from the reaction product gases is done 6~ by dry separation the solids-free gases are free from contaminatior 7 by liquid or liquid vapors~ and there will be no loss of unreacted 8 chloride values by washing.
- 9 The invention is particularly adapted to the production
10 ; of pigmentary titanium dioxide wherein the metal chloride is
11 I titanium tetrachloride which is reacted with oxygen or an oxygen-
12 containing gas at elevated temperatures. The invention also
13 contemplates the introduction, in a kno~n manner of small amounts
14 ¦ of other substances into the reaction chamber for imparting
15 certain desired properties to the pigment, as for example, ;~
16 for promoting the formation of a rutile TiO2 pigment or for
17 effecting a desired particle size. Examples o such additives
18 ¦ are aluminum chloricle introduced into the reaction chamber as
19 ¦¦ ~aseous aluminum chloride, steam or alkali metal compounds,
20~¦ such as for example, sodium and potassium chlorides. It is also
21 jl possible to introduce ~nto the reaction chamber, in a kno~m
22 ~l, manner and after the reaction has taken place between the
23 i¦ titanium tetrachloride and oxygen, other substances such as ¦~
24 ~¦ halides of silicon, titanium, aluminum, zirconium and the like,
25 I¦ which produce a correspondingr metal oxide coating on the pigment
26 1l particles. In this connection, the process according to the
27 1l instant invention is particularly advantageous because freauently
28 1¦ in the sul)sequent addition of these other metal halides into
29 ii the hot reaction product gases a reaction ~-rill occur bet~een 3 il these metal halides and some of the finely divicled titanium l`' 9 -,1,.
. . : .. - . :- - . . .
.. . . .. .
~L 0 ~ 1~ 5~ T
l ~1ioxi(1e particles s~lspc?n~le~l in the gases ~hich reaction may result¦
21 in the formation of titanil1in tetrac]1loride. ~-!o1~ever, in view of 3 i the omission oE gas com~ressors t]le tltani1lm tetrachloride so for~ed 4i is no more cause for troul)le in the furthc?r 1~rocessin~T of the 5 il reaction product gases than the unreacted titaniu~1 tetrachloride 6 1I present in the reaction product gases.
71l Although the invention is described and deined 8 1I particularly ~rith respect to the ~roduction of pigmentary titanium 9l1 dioxide, it ~ill be ul1derstood that the invention is equally lO¦I applicable to thc production of other metal oxides rom corres-ll I ponding metal halides, as for exanl~le, the pro(1uct;on of iron 12 I oxide fro~ iron chlorides, silicon oxi~1e from the c}llorides of .
13 ¦ silicon, anc1 the oxides o:~ al~ninun1 anc1 zirconium from the corres-141¦pondence chlorides. As is well kno~n, most titanium ores are high~y l5i1 Eerriferous and in the manufacture of titanium dioxide pig~ents ~ -; l6~1 Erom such ores largte amol1nts o iron co~po~mcls are ~ormed wl1ich 171l are a lotnd on the ~rocess ancl cannot be utilizec1; or can ~e 18~1 utilized only ~ri~h difficulty. It is custo1~ary~ therefore, l91 especially in the production of titaniwn diocide p1tCTment to first 20i, hene-ficit~te the ore, i.e. to re~ove at least ~art of the`iron -21 i from the ore so that it Till he lower in iron for the manufacture !
22 i~ o titani~1m tetrachloride. ~To~rever? even the titanium tetra- ~, 23 " chloride produced from beneficiated ores 1~ill contain some iron 24 !~ chloride 1~Thich must be separated from the ti~taniu~ tetrachloride.
25 ~' Thus, in both cases fairly large amounts of iron chloride as 26 !,, -Eerric trichloride are l~roc1uced ~'sing the process of this 27 jl invention this ferric trichloric1e may be transormed into iron 28 ~i oxide ~Titho1lt lar~Te e~penditure of energy anc1 1lsed as pigment or 29 ~1 as a source ~aterial in the proc111ction of ~etallic iron.
3 l The invention is ft1rther illustratec1 by the follo~ing ln -.-- ''` , I
. ~
3~ 39~
example which is for purposes of illustration only and not restrictive of the invention which, as mentioned supra is applicable to the production not only of titanium dioxide but also other metal oxides including iron oxide.
EXAMPLE
A reaction chamber was employed which was built essentially like the chamber described in U.S. 3,582,27 Kulling et al which chamber had an inner diameter of 130 mm the length of the chamber below the titanium tetrachloride inlets being about 1000 mm. Into this reaction chamber 96 standard cubic meters per hour of oxygen and 500 kilograms per hour titanium tetrachloride, each of which had been preheated to 250C and 350C respectively were introduced.
` Aluminum chloride was also introduced into the reaction chamber together with the titanium tetrachloride the amount of aluminum chloride added being such that 2% A12O3 was c present in the product titanium dioxide pigment. ~n addition, 32 standard cubic meters per hour carbon monoxide at room temperature were introduced into the reaction chamber and burned in the upper part thereof to provide elevated temperatures for effecting reaction between the titanium tetrachloride and oxygen. The pressure of the reaction product gases in the reaction chamber was about 17 p,sig.
At these temperatures and pressure the reaction went sub-stantially 99.7~ to completion and the reaction product gases leaving the reaction chamber were at a temperature of about 1500C. The reaction product gases leaving the reaction chamber were conducted through cooling means in the form of a 9 meter long cooling pipe of aluminum having 3Q an inner diameter of 100 mm and cooled from the outside by means of water circulation through .. .. . - . .
~043~ f 1 a water jacket. In order to prcvent incru.station o~ the walls 2 of thc cool;ng tnl-e ~ith pig~lent~ 10 kilo~yrams per hour o~ sancl 3 ~ere introduced into the reaction product ~ses prior to intro- ¦
4 duction into the coolin~ pipe. The cooled reaction product ~ases, including the suspended titanium dioxi(te and sand, left the 6,` coolin~ pipe at a temperature of about 400C. ~t this point the 71Ipressure of the gases was only slightly reduced. Thereafter, 8ll the aforesaid cooled reaction product gases ~ere introduced 9 I into a dry filter the filtering sur:Eace of which measured about lO I 5 square meters. In passing through the filterin~ surface the ~ pressure of the reaction product gases decreased by about 0.061 12,~ atmospheres. The sand and the pigment separated ~rom the 13,j reaction product gases ~as carried out of the filter hy means 14 1! f a scre~ conveyor and the sand a~l TiO2 pigment separated and 15 li further processed in known manner. The solids-free gases leaving 16'i the filter lYere at a pressure of about 1~ psig and at a tempera-17 ! ture of about 350C and ~ere directly introduced into a chlorina-18 !l tor for producing additional titanium tetrachloride hy chlorinatio 19 ¦' of titaniferous ore.
20 , 21 , 24 If ' 25 ,l,' 26 , 27 li 28 f ' 29 "
3O '~
.;
- :
. . : .. - . :- - . . .
.. . . .. .
~L 0 ~ 1~ 5~ T
l ~1ioxi(1e particles s~lspc?n~le~l in the gases ~hich reaction may result¦
21 in the formation of titanil1in tetrac]1loride. ~-!o1~ever, in view of 3 i the omission oE gas com~ressors t]le tltani1lm tetrachloride so for~ed 4i is no more cause for troul)le in the furthc?r 1~rocessin~T of the 5 il reaction product gases than the unreacted titaniu~1 tetrachloride 6 1I present in the reaction product gases.
71l Although the invention is described and deined 8 1I particularly ~rith respect to the ~roduction of pigmentary titanium 9l1 dioxide, it ~ill be ul1derstood that the invention is equally lO¦I applicable to thc production of other metal oxides rom corres-ll I ponding metal halides, as for exanl~le, the pro(1uct;on of iron 12 I oxide fro~ iron chlorides, silicon oxi~1e from the c}llorides of .
13 ¦ silicon, anc1 the oxides o:~ al~ninun1 anc1 zirconium from the corres-141¦pondence chlorides. As is well kno~n, most titanium ores are high~y l5i1 Eerriferous and in the manufacture of titanium dioxide pig~ents ~ -; l6~1 Erom such ores largte amol1nts o iron co~po~mcls are ~ormed wl1ich 171l are a lotnd on the ~rocess ancl cannot be utilizec1; or can ~e 18~1 utilized only ~ri~h difficulty. It is custo1~ary~ therefore, l91 especially in the production of titaniwn diocide p1tCTment to first 20i, hene-ficit~te the ore, i.e. to re~ove at least ~art of the`iron -21 i from the ore so that it Till he lower in iron for the manufacture !
22 i~ o titani~1m tetrachloride. ~To~rever? even the titanium tetra- ~, 23 " chloride produced from beneficiated ores 1~ill contain some iron 24 !~ chloride 1~Thich must be separated from the ti~taniu~ tetrachloride.
25 ~' Thus, in both cases fairly large amounts of iron chloride as 26 !,, -Eerric trichloride are l~roc1uced ~'sing the process of this 27 jl invention this ferric trichloric1e may be transormed into iron 28 ~i oxide ~Titho1lt lar~Te e~penditure of energy anc1 1lsed as pigment or 29 ~1 as a source ~aterial in the proc111ction of ~etallic iron.
3 l The invention is ft1rther illustratec1 by the follo~ing ln -.-- ''` , I
. ~
3~ 39~
example which is for purposes of illustration only and not restrictive of the invention which, as mentioned supra is applicable to the production not only of titanium dioxide but also other metal oxides including iron oxide.
EXAMPLE
A reaction chamber was employed which was built essentially like the chamber described in U.S. 3,582,27 Kulling et al which chamber had an inner diameter of 130 mm the length of the chamber below the titanium tetrachloride inlets being about 1000 mm. Into this reaction chamber 96 standard cubic meters per hour of oxygen and 500 kilograms per hour titanium tetrachloride, each of which had been preheated to 250C and 350C respectively were introduced.
` Aluminum chloride was also introduced into the reaction chamber together with the titanium tetrachloride the amount of aluminum chloride added being such that 2% A12O3 was c present in the product titanium dioxide pigment. ~n addition, 32 standard cubic meters per hour carbon monoxide at room temperature were introduced into the reaction chamber and burned in the upper part thereof to provide elevated temperatures for effecting reaction between the titanium tetrachloride and oxygen. The pressure of the reaction product gases in the reaction chamber was about 17 p,sig.
At these temperatures and pressure the reaction went sub-stantially 99.7~ to completion and the reaction product gases leaving the reaction chamber were at a temperature of about 1500C. The reaction product gases leaving the reaction chamber were conducted through cooling means in the form of a 9 meter long cooling pipe of aluminum having 3Q an inner diameter of 100 mm and cooled from the outside by means of water circulation through .. .. . - . .
~043~ f 1 a water jacket. In order to prcvent incru.station o~ the walls 2 of thc cool;ng tnl-e ~ith pig~lent~ 10 kilo~yrams per hour o~ sancl 3 ~ere introduced into the reaction product ~ses prior to intro- ¦
4 duction into the coolin~ pipe. The cooled reaction product ~ases, including the suspended titanium dioxi(te and sand, left the 6,` coolin~ pipe at a temperature of about 400C. ~t this point the 71Ipressure of the gases was only slightly reduced. Thereafter, 8ll the aforesaid cooled reaction product gases ~ere introduced 9 I into a dry filter the filtering sur:Eace of which measured about lO I 5 square meters. In passing through the filterin~ surface the ~ pressure of the reaction product gases decreased by about 0.061 12,~ atmospheres. The sand and the pigment separated ~rom the 13,j reaction product gases ~as carried out of the filter hy means 14 1! f a scre~ conveyor and the sand a~l TiO2 pigment separated and 15 li further processed in known manner. The solids-free gases leaving 16'i the filter lYere at a pressure of about 1~ psig and at a tempera-17 ! ture of about 350C and ~ere directly introduced into a chlorina-18 !l tor for producing additional titanium tetrachloride hy chlorinatio 19 ¦' of titaniferous ore.
20 , 21 , 24 If ' 25 ,l,' 26 , 27 li 28 f ' 29 "
3O '~
.;
- :
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for producing fine particle size titanium dioxide by oxidation of titanium tetrachloride produced by chlorination of corresponding titanium bearing ores, comprising the steps of : feeding preheated gaseous titanium tetrachloride and oxygen into a heated reaction zone and reacting said titanium tetrachloride and oxygen at elevated pressure and a temperature of at least 1000°C. to form titanium doixide suspended in the reaction product gases, including gaseous chlorine, conducting the titanium oxide-burdened reaction product gases from the reaction zone into and through successive cooling and titanium dioxide separating zones, respectively, to cool the reaction product gases down to 200 - 400°C., the pressure of the gases in said reaction zone being in the range of 12 - 20 psig, such that the titanium dioxide free gases exiting from said separation zones are recycled without further compression into a chlorination zone to chlorinate said titanium bearing ore and form additional titanium tetrachloride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA214,598A CA1043982A (en) | 1974-11-25 | 1974-11-25 | Process for the manufacture of fine particle size metal oxides |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA214,598A CA1043982A (en) | 1974-11-25 | 1974-11-25 | Process for the manufacture of fine particle size metal oxides |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043982A true CA1043982A (en) | 1978-12-12 |
Family
ID=4101710
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA214,598A Expired CA1043982A (en) | 1974-11-25 | 1974-11-25 | Process for the manufacture of fine particle size metal oxides |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1043982A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5196181A (en) * | 1989-11-13 | 1993-03-23 | Kronos (Usa), Inc. | Process for the production of titanium dioxide |
| WO2011111848A3 (en) * | 2010-03-08 | 2011-11-10 | National University Corporation Hokkaido University | Method and apparatus for producing metal oxide particles |
-
1974
- 1974-11-25 CA CA214,598A patent/CA1043982A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5196181A (en) * | 1989-11-13 | 1993-03-23 | Kronos (Usa), Inc. | Process for the production of titanium dioxide |
| WO2011111848A3 (en) * | 2010-03-08 | 2011-11-10 | National University Corporation Hokkaido University | Method and apparatus for producing metal oxide particles |
| CN102781822A (en) * | 2010-03-08 | 2012-11-14 | 国立大学法人北海道大学 | Method and apparatus for producing metal oxide particles |
| US9352965B2 (en) | 2010-03-08 | 2016-05-31 | National University Corporation Hokkaido University | Method and apparatus for producing metal oxide particles |
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