CA1052581A - Process for the treatment of calcium titanate - Google Patents
Process for the treatment of calcium titanateInfo
- Publication number
- CA1052581A CA1052581A CA221,279A CA221279A CA1052581A CA 1052581 A CA1052581 A CA 1052581A CA 221279 A CA221279 A CA 221279A CA 1052581 A CA1052581 A CA 1052581A
- Authority
- CA
- Canada
- Prior art keywords
- hydrogen sulphide
- calcium titanate
- calcium
- titanium dioxide
- treatment
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1236—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching
- C22B34/124—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors
- C22B34/125—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors containing a sulfur ion as active agent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1218—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by dry processes
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- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for the treatment of calcium titanate, e.g.
a perovskite ore or concentrate, comprising the step of con-tacting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200°C. is dis-closed. In a preferred embodiment the resulting mixture of titanium dioxide and calcium compounds is treated with a sat-urated aqueous solution of hydrogen sulphide to facilitate separation of the titanium dioxide. The process provides a method of reducing the magnesium and alkaline each content of perovskite.
A process for the treatment of calcium titanate, e.g.
a perovskite ore or concentrate, comprising the step of con-tacting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200°C. is dis-closed. In a preferred embodiment the resulting mixture of titanium dioxide and calcium compounds is treated with a sat-urated aqueous solution of hydrogen sulphide to facilitate separation of the titanium dioxide. The process provides a method of reducing the magnesium and alkaline each content of perovskite.
Description
lOS'~S81 The present invention relates to a process ~or the treatment of calcium titanate with hydrogen sulphide. In particular, the present invention relates to a process ~or the treatment of perovskite ore with hydrogen sulphide.
As used herein the term "perovskite ore" refers to an ore containing calcium titanate in suf~icient quality and quantity so as to be capable of being a source of calcium titanate, or derivatives thereof, and the term "perovskite concentrate" refers to perovskite ore that has been sub~ected to a beneficiation process for the removal of waste material, i.e., gangue.
Pigment grade titanium dioxide may be manufactured by the chlorination of ilmenite or rutile. However, in such chlorination processes calcium, magnesium, strontium, and/or barium compounds may cause process problems. For example, in the chlorination of high titania slags containing calcium, magnesium, strontium and/or barium compounds, these compounds are converted into the corresponding chlorides which, at the temperatures used in the chlorination process, fuse and coat particles of titanium dioxide. The particles so coated may become resistant to chlorine. To overcome this problem of coated particles a portion of the solids in the fluidized bed generally used in such processes may be withdrawn, leached with water to reduce the level of calcium, magnesium, strontium and barium chlorides, dried and returned to the fluidized bed.
In the case of the chlorination of ilmenite the levels of, for example, calcium oxide and magnesium oxide in the ilmenite fed to the chlorinator are preferably less than 0.2 and 1.0 per-cent by weight respectively. However, it is possible to use rutile containing higher levels of calcium and magnesium oxides.
Perovskite is a naturally occurring mineral of c~lcium titanate which may be associated with significant amounts of cal-cium, magnesium, strontium and barium compounds. Perovskite is a potential source of titanium metal or titanium compounds, - 1 - ~
~()5;~58~
especlally titanium dioxide. However, the calciumJ magnesium, strontium and barium content of perovskite deposits may result in the deposits being unsuitable as a ~ource of titanium metal or titanium compounds.
A process for the treatment of calcium ti~anate, especially in the form of perovskite, to reduce the level of magnesium and alkaline earth compounds in said titanate -has now been found.
Accordingly, the present invention provides a pro-cess for the treatment of calcium titanate comprising the stepof contacting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200C.
In an embodiment of the process of the invention the calcium compound so formed is separated from the resultant mix-ture in a subsequent step in the process.
In a further embodiment the titanium dioxlde so formed is separated from the resultant mixture in a subsequent step in the process.
In another embodiment the calcium titanate is in the form of a perovskite concentrate.
The present invention also provideæ a process for the treatment of calcium titanate comprising the sequential steps of (a) contàcting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200C.; and (b) subsequently treating the product of step (a) with a saturated aqueous solution of hydrogen sulphide.
In an embodiment of the process of the invention titanium dioxide is separated from the solution formed in step (b)-In another embodiment the solution formed in step(b) is, after removal of titanium dioxide, treated with carbon dioxide or with an acid.
105'~58~
In the process of the present in~ention calcium titanate is contacted with hydrogen sulphide at temperatures in the range 700 to 1200C. The process may be operable at higher temperatures but at temperatures above about 1200C.
fusion o~ the reaction products tends to occur and problems in the separation of the reaction products may result. Treatment at temperatures below 700C. may occur at slow rates. ~s is illustrated hereinafter in the examples, treatment at about 1000C. for a few, for example two, hours results in high yields of reaction products.
The pressure at which the calcium titanate is con-tacted with hydrogen sulphide is not critical. Preferred pressures are at or above atmospheric pressure. Water is pro-duced during the treatment process and thus high pressures may not be desirable.
The process may be operated as a batch process or as a continuous process. It is preferable that the calcium titanate used in the process be ground to facilitate treatment.
The mesh size of the ground calcium titanate will depend to a large extent on the actual technique used to treat the cal-cium titanate with hydrogen sulphide3 e.g., a fluidized bed reactor may require a smaller particle size than a fixed bed reactor.
Hydrogen sulphide is used in the gaseous form in the high temperature treatment of calcium titanate. In the process the calcium titanate is contacted with an excess of hydrogen sulphide, i.e. an amount in excess of the amount required for stoichiometric reaction of hydro~en s~lphide with calcium titan-ate, and with other compounds associated therewith, under the reaction conditions. Preferably at least a 5 fold excess is used.
It may be possible under some circumstances to use the product of the process of the prese~t invention in another process without ~urther treatment. However, it is preferable to treat the product further, for example, to separate the lOSi~581 titanium dioxide formed from other products o~ the process. A
preferred treatment process is to contact the reaction product with a saturated aqueous solution of hydrogen sulphide. me aqueous solution should be maintained saturated with hydrogen sulphide during the treatment process by addition of hydrogen sulphide, if necessary, so as to facilitate reaction o~ all compounds capable of reacting with hydrogen sulphide. Treat-ment with aqueous hydrogen sulphide solution may be carried out at ambient temperatures or at elevated temperatures. The rate of reaction may be higher at the higher temperatures. Treat-ment with aqueous hydrogen sulphide results in the formation of water-soluble calcium compounds believed to be calcium hydro-sulphide. The insoluble titanium dioxide together with other insoluble matter, e.g., gangue may be separated by known tech-niques, for eXam~le, by filtration or by the use of centri-fuge techniques. me insoluble titanium dioxide so separated may be capable of being used as a feed material for another process, e.g., the aforementioned chlorination process. Alter-natively the titanium dioxide may be purified and used as a feed material for another process or sold as such.
Hydrogen sulphide may be recovered from the aqueous solution of calcium compound by contacting the aqueous solu-tion with gaseous carbon dioxide or with an acid. Preferably any excess of carbon dioxide used is kept to a minimum to reduce the level of carbon dioxide in the hydrogen sulphide that is liberated. The liberated hydrogen sulphide may be recycled, preferably after purification, to those steps in the process where hydrogen sulphide~is utilized or to another process utilizing hydrogen sulphide. Calcium carbonate formed during treatment with carbon dioxide may find application in a ~ariety of end uses. For example, carbon dioxide may be regenerated by heating the calcium carbonate. Hydrogen sulphide may also be recovered by treating the aqueous solution of calcium compound with an acid, e.g., sulphuric or ` lOSZ581 hydrochloric acids. me use of some acids, e.g. s.ulphuric acid, will result in the formation of insoluble calcium salts which may be advantageous, In a preferred embodiment of the process of the pres-ent invent.ion a process is provided where calcium may be sep-arated from titanium dioxide in a process that is potentially non-pollutin~.to the atmosphere or to effluent streams from the process as the reactant hydrogen sulphide may be recycled.
The process of the present invention is operable in the presence of impurities, even reactive impurities, but difficulties may be encountered in the separation of the reaction products or in subse~uent processes utilizing the reaction products. The reactive impurities may include mag-nesium, strontium and barium compounds and other calcium com-l poundæ. m e reactive magnesium, strontium and barium compounds `: form the correspnding sulphides when treated with gaseous hydro-'~ gen sulphide according to the process of the invention. These .~ sulphides are soluble on treatment with aqueous hydrogen sul-phide solution and are separable from the titanium dioxide by the me.thod described hereinabove for the separation of the water-soluble calcium compound. Other compounds may be in-soluble .in the aqueo.us solution of hydrogen sulphide. While ; these insoluble.cQmpounds may be separable from the tltanium ;~ d$ox$de by physical means, e.g., flotatlon, it may be prefer-able to treat the.mixture of lnsoluble cQm~Q~nds and titanium dioxido with an acidj e.~., dilute hydrochloric acid, under conditions where all or some of~the insol.uble compounds but not the tita~1um dioxide, react and form soluble compounds.
Some iron impurities may be separated in this manner. me 3~ re~ctlve calcium compounds include calcium oxide and carbonate which form calcium sulphide on treatment with gaseous hydrogen sulphide in the process of the present invention and thus are ~052581 rable from titanium dioxide by treatment with aqueous hydro-gen sulphide. Other calcium salts, e.g., phosphate, may not react with the gaseous hydrogen sulphide. Beneficiatlon of perovskite will generally reduce the level of such impurities ln the perovsklte.
The calcium titanate that may be used ln the process of the present lnvention may be substantially pure calcium titanate, perovsklte concentrate or, less preferably, perovsklte ore. If the calcium titanate is in the form of perovskite ore it is preferable to sub~ect the perovskite ore to a beneficiation process, thereby forming a perovksite concentrate, before contact-!~ .
ing the perovskite ore with hydrogen sulphide. Such a benefici-ation process, for example beneficiation using gravity and/or flotation techniques, separates a significant amount of waste material, i.e., gangue, prior to treatment of the ore with hydro-gen sulphide, thereby improving the economics of the process.
The process of the present invention is illustrated by the following examples.
EXAMPLE I
, .
3.1833 gms. of synthetic calcium titanate were placed in a small combustion boat in a tube furnace. m e calcium tltanate was heated under a stream of hydrogen sulphide for
As used herein the term "perovskite ore" refers to an ore containing calcium titanate in suf~icient quality and quantity so as to be capable of being a source of calcium titanate, or derivatives thereof, and the term "perovskite concentrate" refers to perovskite ore that has been sub~ected to a beneficiation process for the removal of waste material, i.e., gangue.
Pigment grade titanium dioxide may be manufactured by the chlorination of ilmenite or rutile. However, in such chlorination processes calcium, magnesium, strontium, and/or barium compounds may cause process problems. For example, in the chlorination of high titania slags containing calcium, magnesium, strontium and/or barium compounds, these compounds are converted into the corresponding chlorides which, at the temperatures used in the chlorination process, fuse and coat particles of titanium dioxide. The particles so coated may become resistant to chlorine. To overcome this problem of coated particles a portion of the solids in the fluidized bed generally used in such processes may be withdrawn, leached with water to reduce the level of calcium, magnesium, strontium and barium chlorides, dried and returned to the fluidized bed.
In the case of the chlorination of ilmenite the levels of, for example, calcium oxide and magnesium oxide in the ilmenite fed to the chlorinator are preferably less than 0.2 and 1.0 per-cent by weight respectively. However, it is possible to use rutile containing higher levels of calcium and magnesium oxides.
Perovskite is a naturally occurring mineral of c~lcium titanate which may be associated with significant amounts of cal-cium, magnesium, strontium and barium compounds. Perovskite is a potential source of titanium metal or titanium compounds, - 1 - ~
~()5;~58~
especlally titanium dioxide. However, the calciumJ magnesium, strontium and barium content of perovskite deposits may result in the deposits being unsuitable as a ~ource of titanium metal or titanium compounds.
A process for the treatment of calcium ti~anate, especially in the form of perovskite, to reduce the level of magnesium and alkaline earth compounds in said titanate -has now been found.
Accordingly, the present invention provides a pro-cess for the treatment of calcium titanate comprising the stepof contacting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200C.
In an embodiment of the process of the invention the calcium compound so formed is separated from the resultant mix-ture in a subsequent step in the process.
In a further embodiment the titanium dioxlde so formed is separated from the resultant mixture in a subsequent step in the process.
In another embodiment the calcium titanate is in the form of a perovskite concentrate.
The present invention also provideæ a process for the treatment of calcium titanate comprising the sequential steps of (a) contàcting calcium titanate with an excess of hydrogen sulphide at a temperature in the range of about 700 to 1200C.; and (b) subsequently treating the product of step (a) with a saturated aqueous solution of hydrogen sulphide.
In an embodiment of the process of the invention titanium dioxide is separated from the solution formed in step (b)-In another embodiment the solution formed in step(b) is, after removal of titanium dioxide, treated with carbon dioxide or with an acid.
105'~58~
In the process of the present in~ention calcium titanate is contacted with hydrogen sulphide at temperatures in the range 700 to 1200C. The process may be operable at higher temperatures but at temperatures above about 1200C.
fusion o~ the reaction products tends to occur and problems in the separation of the reaction products may result. Treatment at temperatures below 700C. may occur at slow rates. ~s is illustrated hereinafter in the examples, treatment at about 1000C. for a few, for example two, hours results in high yields of reaction products.
The pressure at which the calcium titanate is con-tacted with hydrogen sulphide is not critical. Preferred pressures are at or above atmospheric pressure. Water is pro-duced during the treatment process and thus high pressures may not be desirable.
The process may be operated as a batch process or as a continuous process. It is preferable that the calcium titanate used in the process be ground to facilitate treatment.
The mesh size of the ground calcium titanate will depend to a large extent on the actual technique used to treat the cal-cium titanate with hydrogen sulphide3 e.g., a fluidized bed reactor may require a smaller particle size than a fixed bed reactor.
Hydrogen sulphide is used in the gaseous form in the high temperature treatment of calcium titanate. In the process the calcium titanate is contacted with an excess of hydrogen sulphide, i.e. an amount in excess of the amount required for stoichiometric reaction of hydro~en s~lphide with calcium titan-ate, and with other compounds associated therewith, under the reaction conditions. Preferably at least a 5 fold excess is used.
It may be possible under some circumstances to use the product of the process of the prese~t invention in another process without ~urther treatment. However, it is preferable to treat the product further, for example, to separate the lOSi~581 titanium dioxide formed from other products o~ the process. A
preferred treatment process is to contact the reaction product with a saturated aqueous solution of hydrogen sulphide. me aqueous solution should be maintained saturated with hydrogen sulphide during the treatment process by addition of hydrogen sulphide, if necessary, so as to facilitate reaction o~ all compounds capable of reacting with hydrogen sulphide. Treat-ment with aqueous hydrogen sulphide solution may be carried out at ambient temperatures or at elevated temperatures. The rate of reaction may be higher at the higher temperatures. Treat-ment with aqueous hydrogen sulphide results in the formation of water-soluble calcium compounds believed to be calcium hydro-sulphide. The insoluble titanium dioxide together with other insoluble matter, e.g., gangue may be separated by known tech-niques, for eXam~le, by filtration or by the use of centri-fuge techniques. me insoluble titanium dioxide so separated may be capable of being used as a feed material for another process, e.g., the aforementioned chlorination process. Alter-natively the titanium dioxide may be purified and used as a feed material for another process or sold as such.
Hydrogen sulphide may be recovered from the aqueous solution of calcium compound by contacting the aqueous solu-tion with gaseous carbon dioxide or with an acid. Preferably any excess of carbon dioxide used is kept to a minimum to reduce the level of carbon dioxide in the hydrogen sulphide that is liberated. The liberated hydrogen sulphide may be recycled, preferably after purification, to those steps in the process where hydrogen sulphide~is utilized or to another process utilizing hydrogen sulphide. Calcium carbonate formed during treatment with carbon dioxide may find application in a ~ariety of end uses. For example, carbon dioxide may be regenerated by heating the calcium carbonate. Hydrogen sulphide may also be recovered by treating the aqueous solution of calcium compound with an acid, e.g., sulphuric or ` lOSZ581 hydrochloric acids. me use of some acids, e.g. s.ulphuric acid, will result in the formation of insoluble calcium salts which may be advantageous, In a preferred embodiment of the process of the pres-ent invent.ion a process is provided where calcium may be sep-arated from titanium dioxide in a process that is potentially non-pollutin~.to the atmosphere or to effluent streams from the process as the reactant hydrogen sulphide may be recycled.
The process of the present invention is operable in the presence of impurities, even reactive impurities, but difficulties may be encountered in the separation of the reaction products or in subse~uent processes utilizing the reaction products. The reactive impurities may include mag-nesium, strontium and barium compounds and other calcium com-l poundæ. m e reactive magnesium, strontium and barium compounds `: form the correspnding sulphides when treated with gaseous hydro-'~ gen sulphide according to the process of the invention. These .~ sulphides are soluble on treatment with aqueous hydrogen sul-phide solution and are separable from the titanium dioxide by the me.thod described hereinabove for the separation of the water-soluble calcium compound. Other compounds may be in-soluble .in the aqueo.us solution of hydrogen sulphide. While ; these insoluble.cQmpounds may be separable from the tltanium ;~ d$ox$de by physical means, e.g., flotatlon, it may be prefer-able to treat the.mixture of lnsoluble cQm~Q~nds and titanium dioxido with an acidj e.~., dilute hydrochloric acid, under conditions where all or some of~the insol.uble compounds but not the tita~1um dioxide, react and form soluble compounds.
Some iron impurities may be separated in this manner. me 3~ re~ctlve calcium compounds include calcium oxide and carbonate which form calcium sulphide on treatment with gaseous hydrogen sulphide in the process of the present invention and thus are ~052581 rable from titanium dioxide by treatment with aqueous hydro-gen sulphide. Other calcium salts, e.g., phosphate, may not react with the gaseous hydrogen sulphide. Beneficiatlon of perovskite will generally reduce the level of such impurities ln the perovsklte.
The calcium titanate that may be used ln the process of the present lnvention may be substantially pure calcium titanate, perovsklte concentrate or, less preferably, perovsklte ore. If the calcium titanate is in the form of perovskite ore it is preferable to sub~ect the perovskite ore to a beneficiation process, thereby forming a perovksite concentrate, before contact-!~ .
ing the perovskite ore with hydrogen sulphide. Such a benefici-ation process, for example beneficiation using gravity and/or flotation techniques, separates a significant amount of waste material, i.e., gangue, prior to treatment of the ore with hydro-gen sulphide, thereby improving the economics of the process.
The process of the present invention is illustrated by the following examples.
EXAMPLE I
, .
3.1833 gms. of synthetic calcium titanate were placed in a small combustion boat in a tube furnace. m e calcium tltanate was heated under a stream of hydrogen sulphide for
2.5 hours at 1000C. me calcium titanate so treated was cooled in an atmosphere of nitrogen. Analysis by X-ray diffrac-tion indicated that all of the calcium titanate had been con-verted to a mixture of calcium sulphide and titanium dioxide;
the error in the X-ray dlffraction method is believed to be less than +10%. Theoretically for such a conversion the weight ; gain of the calcium titanate during treatment with hydrogen sul-phide should be 11.8%; actual weight gain was 12.5%.
the error in the X-ray dlffraction method is believed to be less than +10%. Theoretically for such a conversion the weight ; gain of the calcium titanate during treatment with hydrogen sul-phide should be 11.8%; actual weight gain was 12.5%.
3.3758 gms. of the above mixture of calcium sulphide and titanium dioxide were leached for 30 minutes at room temp-erature with an excess of saturated aqueous hydrogen sulphide ~ 105;~581 '~olution. The solution was filtered ~nd the residue when dried weighed 1.8514 gms. Analysis o~ the residue showed that it was comprised of 87.5% titanium dioxide and 2.7~ calcium, i.e., 91.5% of the theoretical yield for the conversion of cal-cium sulphide to calcium hydrosulphide. An excess of carbon dioxide was passed through the filtrate for about 30 minutes at room temperature. The precipitate so formed weighed 1.1971 gms. when dried, i.e., 89.3% of the theoretical yield of the expected product, calcium carbonate.
EXAMPLE II
2.6250 gms. of perovskite ore of analysis 5.6~ Fe, 20.3~ Ca, 30.9~ Ti, 3.0% SiO2 and being ground so that 28~ was of a -I00/+200 mesh size and 65% was of a -200/+325 mesh size, were treated with hydrogen sulphide at 1200C. for 2 hours using the procedure described in Example I. A 11.8% weight gain was obtained. X-ray diffraction indicated that the prod-uct was a mixture of calcium sulphide, titanium dioxide and iron sulphide, no perovskite or ilmenite was detected. The mixture was leached with an excess of a saturated aqueous sol-ution of hydrogen sulphide. After filtration the dried residueshowed that 90.7~ of the theoretical weight loss for the con-version of calcium sulphide to calcium hydrosulphide had been obtained. m e filtrate was treated with carbon dioxide as des-cribed in Example I and the precipitate formed was 67% of the theoretical yield for calcium carbonate.
_ AMPLE III
Samples of the perovskite of Example II were treated with hydrogen sulphide for 3 hours at various temperatures us-ing the procedure of Example I. The gain in weight of the samples is given in Table I.
lOSZ581 TABLE I
Temperature (C.) Weight Gain (%) Comments 600 0 No reaction 700 2.6 800 3.6 900 5.7 1000 9 . O
1200 11.8 Trace of perovskite (analysis by X-ray diffraction)
EXAMPLE II
2.6250 gms. of perovskite ore of analysis 5.6~ Fe, 20.3~ Ca, 30.9~ Ti, 3.0% SiO2 and being ground so that 28~ was of a -I00/+200 mesh size and 65% was of a -200/+325 mesh size, were treated with hydrogen sulphide at 1200C. for 2 hours using the procedure described in Example I. A 11.8% weight gain was obtained. X-ray diffraction indicated that the prod-uct was a mixture of calcium sulphide, titanium dioxide and iron sulphide, no perovskite or ilmenite was detected. The mixture was leached with an excess of a saturated aqueous sol-ution of hydrogen sulphide. After filtration the dried residueshowed that 90.7~ of the theoretical weight loss for the con-version of calcium sulphide to calcium hydrosulphide had been obtained. m e filtrate was treated with carbon dioxide as des-cribed in Example I and the precipitate formed was 67% of the theoretical yield for calcium carbonate.
_ AMPLE III
Samples of the perovskite of Example II were treated with hydrogen sulphide for 3 hours at various temperatures us-ing the procedure of Example I. The gain in weight of the samples is given in Table I.
lOSZ581 TABLE I
Temperature (C.) Weight Gain (%) Comments 600 0 No reaction 700 2.6 800 3.6 900 5.7 1000 9 . O
1200 11.8 Trace of perovskite (analysis by X-ray diffraction)
Claims (12)
1. A process for the treatment of calcium titanate comprising the step of contacting calcium titanate with hydrogen sulphide at a temperature in the range of about 700 to 1200°C, the amount of hydrogen sulphide being in excess of the stoi-chiometric amount for the reaction of hydrogen sulphide and calcium titanate.
2. The process of Claim 1 which additionally com-prises the step of separating a calcium compound from the reaction mixture resulting from the contacting of the calcium titanate with the hydrogen sulphide.
3. The process of Claim 1 which additionally com-prises the step of spearating titanium dioxide from the reaction mixture resulting from the contacting of the calcium titanate with the hydrogen sulphide.
4. The process of any one of Claim 1, Claim 2 and Claim 3 in which the temperature is in the range 900 to 1200°C.
5. The process of any one of Claim 1, Claim 2 and Claim 3 in which the calcium titanate is a perovskite concen-trate.
6. A process for the treatment of calcium titanate comprising the sequential steps of (a) contacting calcium titanate with hydrogen sulphide at a temperature in the range of about 700 to 1200°C, the amount of hydrogen sulphide being in excess of the stoi-chiometric amount for the reaction of hydrogen sulphide and calcium titanate; and (b) subsequently treating the product of step (a) with a saturated aqueous solution of hydrogen sulphide.
7. The process of Claim 6 which additionally com-prises the step of separating titanium dioxide from the reaction mixture resulting from the contacting of the calcium titanate with the hydrogen sulphide.
8. The process of Claim 6 which additionally com-prises the steps of (c) separating titanium dioxide from the aqueous reaction mixture of step (b), and (d) treating the aqueous solution obtained on the separation of titanium dioxide from the aqueous reaction mix-ture in step (c) with carbon dioxide or an acid, and recovering hydrogen sulphide.
9. The process of Claim 8 in which carbon dioxide is used in step (d) and in which the hydrogen sulphide so obtained is subsequently separated from the carbon dioxide.
10. The process of Claim 8 in which the hydrogen sulphide that is obtained in step (d) forms at least part of the hydrogen sulphide of step (a) or step (b).
11. The process of any one of Claim 6, Claim 8 and Claim 10 in which the temperature is in the range 900 to 1200°C.
12. The process of any one of Claim 6, Claim 8 and Claim 10 in which the calcium titanate is a perovskite concen-trate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA221,279A CA1052581A (en) | 1975-03-04 | 1975-03-04 | Process for the treatment of calcium titanate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA221,279A CA1052581A (en) | 1975-03-04 | 1975-03-04 | Process for the treatment of calcium titanate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1052581A true CA1052581A (en) | 1979-04-17 |
Family
ID=4102422
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA221,279A Expired CA1052581A (en) | 1975-03-04 | 1975-03-04 | Process for the treatment of calcium titanate |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1052581A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016007020A1 (en) | 2014-07-08 | 2016-01-14 | Avertana Limited | Extraction of products from titanium-bearing minerals |
| WO2020122740A1 (en) | 2018-12-14 | 2020-06-18 | Avertana Limited | Methods of extraction of products from titanium-bearing materials |
-
1975
- 1975-03-04 CA CA221,279A patent/CA1052581A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016007020A1 (en) | 2014-07-08 | 2016-01-14 | Avertana Limited | Extraction of products from titanium-bearing minerals |
| WO2016007021A1 (en) | 2014-07-08 | 2016-01-14 | Avertana Limited | Extraction of products from titanium-bearing minerals |
| WO2020122740A1 (en) | 2018-12-14 | 2020-06-18 | Avertana Limited | Methods of extraction of products from titanium-bearing materials |
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