CA1234990A - Process of producing an tio.sub.2 concentrate from tio.sub.2-containing starting materials - Google Patents
Process of producing an tio.sub.2 concentrate from tio.sub.2-containing starting materialsInfo
- Publication number
- CA1234990A CA1234990A CA000481721A CA481721A CA1234990A CA 1234990 A CA1234990 A CA 1234990A CA 000481721 A CA000481721 A CA 000481721A CA 481721 A CA481721 A CA 481721A CA 1234990 A CA1234990 A CA 1234990A
- Authority
- CA
- Canada
- Prior art keywords
- concentrate
- tio2
- leaching stage
- dilute
- sulfuric acid
- 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
- C22B34/1204—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 preliminary treatment of ores or scrap to eliminate non- titanium constituents, e.g. iron, without attacking the titanium constituent
- C22B34/1213—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 preliminary treatment of ores or scrap to eliminate non- titanium constituents, e.g. iron, without attacking the titanium constituent by wet processes, e.g. using leaching methods or flotation techniques
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A process is described in which a TiO2 concentrate is recovered from TiO2-containing starting materials, where-in said starting materials are leached with dilute mineral acid at an elevated temperature and the separated residue is treated with reducing agents and is subsequently leached with dilute mineral acid at an elevated temperature. In order to produce a high-grade TiO2 concentrate with the aid of dilute waste sulfuric acid, which constitutes a waste pro-duct and is discarded in the process, a) the starting material is leached in the first leaching stage with dilute waste sul-furic acid at a temperature of 160 to 180°C and under super-atmospheric pressure to produce an intermediate concentrate having a TiO2 content of about 60% or more, b) the intermediate concentrate is filtered off and is reduced by a treatment with a carbon-containing fuel after an optional oxidation, c) the dilute waste sulfuric acid obtained as a filtrate from the first leaching stage is used to leach the reduced product of step b) at temperatures between 60 and 180°C and, if desired, under superatmospheric pressure so as to consume all free sulfuric acid and to obtain a concentrate having a TiO2 content of 80% or more, and d) iron sulfate heptahydrate is crystallized in the filtrate.
A process is described in which a TiO2 concentrate is recovered from TiO2-containing starting materials, where-in said starting materials are leached with dilute mineral acid at an elevated temperature and the separated residue is treated with reducing agents and is subsequently leached with dilute mineral acid at an elevated temperature. In order to produce a high-grade TiO2 concentrate with the aid of dilute waste sulfuric acid, which constitutes a waste pro-duct and is discarded in the process, a) the starting material is leached in the first leaching stage with dilute waste sul-furic acid at a temperature of 160 to 180°C and under super-atmospheric pressure to produce an intermediate concentrate having a TiO2 content of about 60% or more, b) the intermediate concentrate is filtered off and is reduced by a treatment with a carbon-containing fuel after an optional oxidation, c) the dilute waste sulfuric acid obtained as a filtrate from the first leaching stage is used to leach the reduced product of step b) at temperatures between 60 and 180°C and, if desired, under superatmospheric pressure so as to consume all free sulfuric acid and to obtain a concentrate having a TiO2 content of 80% or more, and d) iron sulfate heptahydrate is crystallized in the filtrate.
Description
Thi~ inventian relste3 ko a prooes~ o~ producing a TiO2 concentrate from TiOz-containlng ~tarting materials which are treated ~th dilute waste sul~uric ~cld e.g. acid that has become available in the production of TiO2 pigmeni.
- It l~ known from U.S.-Patent 3,777,013 tD produce synthetic rutile by a treatment of llmenite with dilute mlnëral acld in a two-stage leaching process. In the kno~n prDces~, ilmen~te i9 treated wlth dllute hydrochlDric acld ln a flrst leaohlng ~tage tD dissDlve irnn oxide, the ae-parated sDlids are treated at temperatures up to 500C
with a reduc1ng gas in ord~r to reduce the higher iron ox~des, the reduced ~olid~ are leached wlth dilute hydro-chlDric acid In a second lèaching qtage, and the residue, which 19 requirèd tc contain more than 90% TiOz, 1~ sepa-rated. Each leaching stPp i9 carried out at temperatures between 90 ano 110C. The known process has the disadvantage that the leaching ta~es considerable time and the process cannot be carried out with waste acid~ The sorrosion of structural materlals by HCl i9 sn enormous problem, ~hich ~,.
- It l~ known from U.S.-Patent 3,777,013 tD produce synthetic rutile by a treatment of llmenite with dilute mlnëral acld in a two-stage leaching process. In the kno~n prDces~, ilmen~te i9 treated wlth dllute hydrochlDric acld ln a flrst leaohlng ~tage tD dissDlve irnn oxide, the ae-parated sDlids are treated at temperatures up to 500C
with a reduc1ng gas in ord~r to reduce the higher iron ox~des, the reduced ~olid~ are leached wlth dilute hydro-chlDric acid In a second lèaching qtage, and the residue, which 19 requirèd tc contain more than 90% TiOz, 1~ sepa-rated. Each leaching stPp i9 carried out at temperatures between 90 ano 110C. The known process has the disadvantage that the leaching ta~es considerable time and the process cannot be carried out with waste acid~ The sorrosion of structural materlals by HCl i9 sn enormous problem, ~hich ~,.
- 2 ~ 3~3~
can be controlled only at a high structural arld financial expenditure. Besides, t}-le process results in the Eormation of solutions of metal chlorides in hydrochloric acid and said solutions can be disposed oE only with diEficulty.
Unless said solutions are regenera-ted for a recovexy and recycling of hydrochloric acid, the process cannot be carried out economically because of the high cos-ts of hydrochloric acid.
It would be advantageous to be able to produce TiO2 concentrate from TiO2-containing starting materials with the aid o~ dilute waste sulfuric acid.
The present invention provides a process for recovering a TiO2 concentrate from an ilmenite s-tarting material which contains TiO2, FeO, and Fe2O3, wherein said ilmenite is leached with dilute mineral acid at an elevated temperature, and a separated residue is treated with a reducing agent, and subsequently leached with dilute mineral acid at an elevated temperature,, which process comprises the steps of:
(a) leaching the ilmeni-te starting material which has been sub~ected only -to mechanical comminution in a first leaching s-tage with dilute waste sulfuric acid at a temperature of 160 to 180 C under a superatmospheric pressure to produce an intermediate concentra-te having a TiO2 content of about 60~;
(b) filtering -the intermediate concentrate -to remove a firs-t leaching stage filtrate comprising dilute sulfuric acid;
(c) oxidizing -the intermediate concentrate to destroy the crystal lattice of the ilmenite and to -transform the FeO therein to Fe2O3;
(d) reducing the in-termediate concentrate oxidized according to step (c) to convert the iron in the Fe2O3 contained therein to metallic iron, by reduction with a solid, carbon-containing Euel;
(e) leaching the intermediate c~ncent:rate treated accordin~ to step (d) in a second ~eaching stage using the first leaching s-tage Eiltrate comprising dilute sulfuric acid ob-tained during step (b), at a -temperature of 60 to 80 C, so as to consume substan-tially all remaining free sulfuric acid and obtain a concentrate having a high TiO2 content in excess of 80~;
(f) filtering the concentrate having a high TiO2 content in excess of 80% to remove a second leaching stage filtra-te containing iron sulfate heptahydrate, to recover the concentrate having a high TiO2 content; and (g) crytstallizing the iron sulfate heptahydrate out of said second leaching stage fil-trate.
In accordance with the presen-t invention a concentrate having a TiO2 content in excess of 80% may be obtained.
In -the process in accordance with the invention the TiO2-containing starting ma-terial may be mechanically pretreated. The starting material is ilmenite. The ilmenite, which may be Eine-grained and may have a particle size below 60 micrometers and may be compsed, e.g., of 45%
TiO2 34% F'eO, 12% Fe2O3, 5% MgO, ~ SiO2, may be fed -to a pressure reactor, in which dilute waste sulfuric acid obtained in the production of TiO2 is added. The dilute wate sulfuric acid usually con-tains 20 to 25~ free sulfuric acid. The ratio of dilute waste sulfuric acid to TiO2-containing raw material is so selected that the sulfuric acid con-tained in the dilu-te waste sulfuric acid which is used is virtually completely consumed in the entire process, specifically in the two leaching stages, and the residual conten-t is less than 1%. The mean reaction time or dwell time in the reactor is generally 0.5 to 2 hours and - 3a -preferably about 1 ho-lr. The treatment, for 0xample, in the first leaching stage at a -tempera-ture of 180 C and a pressure of 0 bars ~1 ~3~
results aFter a dwell tlme oF only 1 hour in a subst3ntial increase in concentratiorl and in an intermedlate concentr2te which contain3 abnut 65~ T10z ~hen the ~tarting material conta~ned 45~ TiOz~
When the reaction has been terminated and the pressure reactor has been pressure-relieved, the solids are separated by means of conventional ~eparating unitsl such as rotary filters, filter presses, or rentrifuge3. The intermediate concentrate has an average TiO2 content nf about 60% orl a dry basis and i5 reduced in a manner ~nown per se in known equipment, such as a ~luidized bed furnace or rotary kiln, by a treatment with solid carbonaceDus fuel, such as brown coal or true coal. In that treatment the iron cont;ent is reduced virtually entirely to metallic iron~ The retiuction carl be controlled to eFFect any desired oe~ree of reduction of iron from 1'~ to about 95~
The reauction may be ~receded oy an oxidizing treatment if the mineralogic211y combined lron cannot di-rectly be reduGed to metallic iron owing to the degree to ~hich the ilmErlite used, for example, as a starting product9 has been weathered. That oxidizing treatment results in a d~truction of the crystal lattice of the ilmenite and in a transf~rrnation of iron to Fe203, ~hich can easily be re-duced to iron metal tnereafter.
~ 53~
The concentrate contains iron more or less com-pletely in metallic form 9nd 19 treated ln a second leachlng stage ~n a presc7ure-resistant suitable reactor at tempera-tures oF 60 to 180~C and, if desired, under a C7uperat~0s-pherlc pressure with the fLltrate which has been obtaLned fro7n the first leaching stage and is depleted in sulFuric acld. The reaction is preferably effected at temDeratures of 50 to ~O~C under normal pressure. T~e reaction rate wlll be ~ncreased and the dwell time can be shortened if the leaching is ef~erted at temperatures above 10DDC, particu-larly bet~een 1b~ and 1~0D~. In the second leaching stage all metallic iron is aissolved with evolution of hydrogen and the free acid still ?resent in the Filtrate from the first leaching stage is consumedO The second leaching stage results in the Formation of a TiO2 concentrate which cantain=7 8U~ TiO2 on a dry ba5is. L~hen the concentrate has been removed, the residu31 Filtrate consists of a ferrous sulfate sDlution, which contains less than 1~ rree H7504 That slightl.y asid iron sulfate solution is supplied to a conventional vacuum orystaLlizor, in whi~h the iron sulfate i5 crystalli.zed 3S iron sulfate heptahydrate After t~e seDaration of the crystallized iron sulfate, the rP~aining filtrate or centrifugate may be ne~-tra-lized with :Lime so tn3t any residual iron and res}dual sul-fate in the solution are coprecipitated as iron hydroxide and gypsum, respeotively.
~l~3~3~
That mixture of lron hydroxide ~3nd gypsum~llaY be separated in cnnventional manner by means of rotary filters.
The moist ~olids can then safely be disposed of on a ~olids dump. The remaining sewage i5 virtually neutral and contains up tn Z grams gypsum per liter.
The invention affords the following advantages - A high-grade TiOz concentrate i5 produced from a base raw material;
- dilute waste sulfuric acid constituting a waste product is used and dispo~ed of and it9 conten~ of free sulfuric acid is utilized;
-~the iron cnntellt of ilmenite i9 transformed tD irDn sulfate heptahydrate, which can be used directly, e.g., in the purification of sewage, or the reS04 heptahydrate can be decomposed to r e203 and SO2/SO3 in a plant for pr~ducing sulFurlc acid frDm oyr1tes;
- the fDrmation of polluants is minimized.
The invention will be explailled more in detail and by way of e~ample with reference t~ the illust~ated flow sche~e.
A react~r ~hich is pro~idea ~ith a stirrer and des~gned tD resist ~ressure i9 supplied llith dilute llaste sulfuric acia fDrmed in the production of TiOz pigment and containing 24~ free sulfuric acid, and ~ith ilmenite having a particle size 3elow r O micrometers and composed of 45 TiOz, 34~ reD~ 1Z-~ e2a~s 5~ MgO, 4h SiOz~ The charge is leached for one hour at a temperature nf 1~0D~ and under a pressure of 1D bars. ~n lnter~ediate concentrate composed of 65~ TiO2, 29r~ FeO/Fe203 and 6~ gangue is ~iltered off.
After an addition of fine-grainPd coalg that intermeoiate concentrate is ~upplied to a reactor, in which a circulating fluidized bed is maintainedO The mean dwell time in that reactor amounts to about 30 minutes at abDut 8~D tD 1000C.
The reduced concentrate cDntains 7~ TiOz, 23~ metallic iron and 7~ gangue. The cooled solids are fed to anDther reactor, which is of the same type as that used tn the -First stage and which is supDlied with the filtrate ~rom the first leaching stage. That filtrate consists of a dilute waste sulFuric acid, which contains about 10h H2504. Leachinc is carried out for 1 hour with stirrino and at a tempera-ture of 100DC and a pressure of 1 barO The dwell time can be conslderably reoucea if the temperature is increased to aDout 16D to 1~0~C and a corre~pondino pressure iB applied.
A TlOz concentrate which cDntains m3re than au-~ TiU2 is re-; co~ered by Filtration. The filtrete cDnsists of a sli~htly acid iron sulfate -olution containins less than 1'~ free sulfuric acid an5 is supplied to 3 vacuum crystallizer. Iron sulfate heptahyorate i9 crystallizeo in that crystallizer and is ~eparated. T~e mother liquor is neutrali7ed. The gypsum which is t~us formed contains some iron hydroxide and is Filtered off anc can be dumped. The sewage is neutral and contains a~out Z nrams ~aS04 per liter and can be dis carded ~nto the receiving body of water.
can be controlled only at a high structural arld financial expenditure. Besides, t}-le process results in the Eormation of solutions of metal chlorides in hydrochloric acid and said solutions can be disposed oE only with diEficulty.
Unless said solutions are regenera-ted for a recovexy and recycling of hydrochloric acid, the process cannot be carried out economically because of the high cos-ts of hydrochloric acid.
It would be advantageous to be able to produce TiO2 concentrate from TiO2-containing starting materials with the aid o~ dilute waste sulfuric acid.
The present invention provides a process for recovering a TiO2 concentrate from an ilmenite s-tarting material which contains TiO2, FeO, and Fe2O3, wherein said ilmenite is leached with dilute mineral acid at an elevated temperature, and a separated residue is treated with a reducing agent, and subsequently leached with dilute mineral acid at an elevated temperature,, which process comprises the steps of:
(a) leaching the ilmeni-te starting material which has been sub~ected only -to mechanical comminution in a first leaching s-tage with dilute waste sulfuric acid at a temperature of 160 to 180 C under a superatmospheric pressure to produce an intermediate concentra-te having a TiO2 content of about 60~;
(b) filtering -the intermediate concentrate -to remove a firs-t leaching stage filtrate comprising dilute sulfuric acid;
(c) oxidizing -the intermediate concentrate to destroy the crystal lattice of the ilmenite and to -transform the FeO therein to Fe2O3;
(d) reducing the in-termediate concentrate oxidized according to step (c) to convert the iron in the Fe2O3 contained therein to metallic iron, by reduction with a solid, carbon-containing Euel;
(e) leaching the intermediate c~ncent:rate treated accordin~ to step (d) in a second ~eaching stage using the first leaching s-tage Eiltrate comprising dilute sulfuric acid ob-tained during step (b), at a -temperature of 60 to 80 C, so as to consume substan-tially all remaining free sulfuric acid and obtain a concentrate having a high TiO2 content in excess of 80~;
(f) filtering the concentrate having a high TiO2 content in excess of 80% to remove a second leaching stage filtra-te containing iron sulfate heptahydrate, to recover the concentrate having a high TiO2 content; and (g) crytstallizing the iron sulfate heptahydrate out of said second leaching stage fil-trate.
In accordance with the presen-t invention a concentrate having a TiO2 content in excess of 80% may be obtained.
In -the process in accordance with the invention the TiO2-containing starting ma-terial may be mechanically pretreated. The starting material is ilmenite. The ilmenite, which may be Eine-grained and may have a particle size below 60 micrometers and may be compsed, e.g., of 45%
TiO2 34% F'eO, 12% Fe2O3, 5% MgO, ~ SiO2, may be fed -to a pressure reactor, in which dilute waste sulfuric acid obtained in the production of TiO2 is added. The dilute wate sulfuric acid usually con-tains 20 to 25~ free sulfuric acid. The ratio of dilute waste sulfuric acid to TiO2-containing raw material is so selected that the sulfuric acid con-tained in the dilu-te waste sulfuric acid which is used is virtually completely consumed in the entire process, specifically in the two leaching stages, and the residual conten-t is less than 1%. The mean reaction time or dwell time in the reactor is generally 0.5 to 2 hours and - 3a -preferably about 1 ho-lr. The treatment, for 0xample, in the first leaching stage at a -tempera-ture of 180 C and a pressure of 0 bars ~1 ~3~
results aFter a dwell tlme oF only 1 hour in a subst3ntial increase in concentratiorl and in an intermedlate concentr2te which contain3 abnut 65~ T10z ~hen the ~tarting material conta~ned 45~ TiOz~
When the reaction has been terminated and the pressure reactor has been pressure-relieved, the solids are separated by means of conventional ~eparating unitsl such as rotary filters, filter presses, or rentrifuge3. The intermediate concentrate has an average TiO2 content nf about 60% orl a dry basis and i5 reduced in a manner ~nown per se in known equipment, such as a ~luidized bed furnace or rotary kiln, by a treatment with solid carbonaceDus fuel, such as brown coal or true coal. In that treatment the iron cont;ent is reduced virtually entirely to metallic iron~ The retiuction carl be controlled to eFFect any desired oe~ree of reduction of iron from 1'~ to about 95~
The reauction may be ~receded oy an oxidizing treatment if the mineralogic211y combined lron cannot di-rectly be reduGed to metallic iron owing to the degree to ~hich the ilmErlite used, for example, as a starting product9 has been weathered. That oxidizing treatment results in a d~truction of the crystal lattice of the ilmenite and in a transf~rrnation of iron to Fe203, ~hich can easily be re-duced to iron metal tnereafter.
~ 53~
The concentrate contains iron more or less com-pletely in metallic form 9nd 19 treated ln a second leachlng stage ~n a presc7ure-resistant suitable reactor at tempera-tures oF 60 to 180~C and, if desired, under a C7uperat~0s-pherlc pressure with the fLltrate which has been obtaLned fro7n the first leaching stage and is depleted in sulFuric acld. The reaction is preferably effected at temDeratures of 50 to ~O~C under normal pressure. T~e reaction rate wlll be ~ncreased and the dwell time can be shortened if the leaching is ef~erted at temperatures above 10DDC, particu-larly bet~een 1b~ and 1~0D~. In the second leaching stage all metallic iron is aissolved with evolution of hydrogen and the free acid still ?resent in the Filtrate from the first leaching stage is consumedO The second leaching stage results in the Formation of a TiO2 concentrate which cantain=7 8U~ TiO2 on a dry ba5is. L~hen the concentrate has been removed, the residu31 Filtrate consists of a ferrous sulfate sDlution, which contains less than 1~ rree H7504 That slightl.y asid iron sulfate solution is supplied to a conventional vacuum orystaLlizor, in whi~h the iron sulfate i5 crystalli.zed 3S iron sulfate heptahydrate After t~e seDaration of the crystallized iron sulfate, the rP~aining filtrate or centrifugate may be ne~-tra-lized with :Lime so tn3t any residual iron and res}dual sul-fate in the solution are coprecipitated as iron hydroxide and gypsum, respeotively.
~l~3~3~
That mixture of lron hydroxide ~3nd gypsum~llaY be separated in cnnventional manner by means of rotary filters.
The moist ~olids can then safely be disposed of on a ~olids dump. The remaining sewage i5 virtually neutral and contains up tn Z grams gypsum per liter.
The invention affords the following advantages - A high-grade TiOz concentrate i5 produced from a base raw material;
- dilute waste sulfuric acid constituting a waste product is used and dispo~ed of and it9 conten~ of free sulfuric acid is utilized;
-~the iron cnntellt of ilmenite i9 transformed tD irDn sulfate heptahydrate, which can be used directly, e.g., in the purification of sewage, or the reS04 heptahydrate can be decomposed to r e203 and SO2/SO3 in a plant for pr~ducing sulFurlc acid frDm oyr1tes;
- the fDrmation of polluants is minimized.
The invention will be explailled more in detail and by way of e~ample with reference t~ the illust~ated flow sche~e.
A react~r ~hich is pro~idea ~ith a stirrer and des~gned tD resist ~ressure i9 supplied llith dilute llaste sulfuric acia fDrmed in the production of TiOz pigment and containing 24~ free sulfuric acid, and ~ith ilmenite having a particle size 3elow r O micrometers and composed of 45 TiOz, 34~ reD~ 1Z-~ e2a~s 5~ MgO, 4h SiOz~ The charge is leached for one hour at a temperature nf 1~0D~ and under a pressure of 1D bars. ~n lnter~ediate concentrate composed of 65~ TiO2, 29r~ FeO/Fe203 and 6~ gangue is ~iltered off.
After an addition of fine-grainPd coalg that intermeoiate concentrate is ~upplied to a reactor, in which a circulating fluidized bed is maintainedO The mean dwell time in that reactor amounts to about 30 minutes at abDut 8~D tD 1000C.
The reduced concentrate cDntains 7~ TiOz, 23~ metallic iron and 7~ gangue. The cooled solids are fed to anDther reactor, which is of the same type as that used tn the -First stage and which is supDlied with the filtrate ~rom the first leaching stage. That filtrate consists of a dilute waste sulFuric acid, which contains about 10h H2504. Leachinc is carried out for 1 hour with stirrino and at a tempera-ture of 100DC and a pressure of 1 barO The dwell time can be conslderably reoucea if the temperature is increased to aDout 16D to 1~0~C and a corre~pondino pressure iB applied.
A TlOz concentrate which cDntains m3re than au-~ TiU2 is re-; co~ered by Filtration. The filtrete cDnsists of a sli~htly acid iron sulfate -olution containins less than 1'~ free sulfuric acid an5 is supplied to 3 vacuum crystallizer. Iron sulfate heptahyorate i9 crystallizeo in that crystallizer and is ~eparated. T~e mother liquor is neutrali7ed. The gypsum which is t~us formed contains some iron hydroxide and is Filtered off anc can be dumped. The sewage is neutral and contains a~out Z nrams ~aS04 per liter and can be dis carded ~nto the receiving body of water.
Claims (5)
1. In a process for recovering a TiO2 concentrate from an ilmenite starting material which contains TiO2, FeO, and Fe2O3, wherein said ilmenite is leached with dilute mineral acid at an elevated temperature, and a separated residue is treated with a reducing agent, and subsequently leached with dilute mineral acid at an elevated temperature, the improvement which comprises the steps of:
(a) leaching the ilmenite starting material which has been subjected only to mechanical comminution in a first leaching stage with dilute waste sulfuric acid at a temperature of 160 to 180° C under a superatmospheric pressure to produce an intermediate concentrate having a TiO2 content of about 60%;
(b) filtering the intermediate concentrate to remove a first leaching stage filtrate comprising dilute sulfuric acid;
(c) oxidizing the intermediate concentrate to destroy the crystal lattice of the ilmenite and to transform the FeO therein to Fe2O3;
(d) reducing the intermediate concentrate oxidized according to step (c) to convert the iron in the Fe2O3 contained therein to metallic iron, by reduction with a solid, carbon-containing fuel;
(e) leaching the intermediate concentrate treated according to step (d) in a second leaching stage using the first leaching stage filtrate comprising dilute sulfuric acid obtained during step (b), at a temperature of 60 to 80° C, so as to consume substantially all remaining free sulfuric acid and obtain a concentrate having a high TiO2 content in excess of 80%, (f) filtering the concentrate having a high TiO2 content in excess of 80% to remove a second leaching stage filtrate containing iron sulfate heptahydrate, to recover the concentrate having a high TiO2 content; and (g) crytstallizing the iron sulfate heptahydrate out of said second leaching stage filtrate.
(a) leaching the ilmenite starting material which has been subjected only to mechanical comminution in a first leaching stage with dilute waste sulfuric acid at a temperature of 160 to 180° C under a superatmospheric pressure to produce an intermediate concentrate having a TiO2 content of about 60%;
(b) filtering the intermediate concentrate to remove a first leaching stage filtrate comprising dilute sulfuric acid;
(c) oxidizing the intermediate concentrate to destroy the crystal lattice of the ilmenite and to transform the FeO therein to Fe2O3;
(d) reducing the intermediate concentrate oxidized according to step (c) to convert the iron in the Fe2O3 contained therein to metallic iron, by reduction with a solid, carbon-containing fuel;
(e) leaching the intermediate concentrate treated according to step (d) in a second leaching stage using the first leaching stage filtrate comprising dilute sulfuric acid obtained during step (b), at a temperature of 60 to 80° C, so as to consume substantially all remaining free sulfuric acid and obtain a concentrate having a high TiO2 content in excess of 80%, (f) filtering the concentrate having a high TiO2 content in excess of 80% to remove a second leaching stage filtrate containing iron sulfate heptahydrate, to recover the concentrate having a high TiO2 content; and (g) crytstallizing the iron sulfate heptahydrate out of said second leaching stage filtrate.
2. A process according to claim 1, characterized in that the intermediate concentrate obtained in the first leaching stage is reduced in a circulating fluidized bed.
3. A process according to claim 1, characterized in that the intermediate concentrate obtained in the first leaching stage is reduced in a rotary kiln.
4. A process according to claim 1, 2 or 3, characterized in that coal is used as a solid fuel.
5. A process according to claim 1, 2 or 3, characterized in that the intermediate concentrate is leached in the second leaching stage at temperatures up to 100° C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843418269 DE3418269A1 (en) | 1984-05-17 | 1984-05-17 | METHOD FOR PRODUCING A TIO (DOWN ARROW) 2 (ARROW DOWN) CONCENTRATES FROM TIO (DOWN ARROW) 2 (ARROW DOWN) CONTAINERS |
| DEP3418269.1 | 1984-05-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1234990A true CA1234990A (en) | 1988-04-12 |
Family
ID=6236069
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000481721A Expired CA1234990A (en) | 1984-05-17 | 1985-05-16 | Process of producing an tio.sub.2 concentrate from tio.sub.2-containing starting materials |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0164777B1 (en) |
| CA (1) | CA1234990A (en) |
| DE (2) | DE3418269A1 (en) |
| IN (1) | IN163285B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7625536B2 (en) | 2005-10-18 | 2009-12-01 | Millennium Inorganic Chemicals, Inc. | Titaniferous ore beneficiation |
| CN113443649A (en) * | 2021-07-13 | 2021-09-28 | 攀钢集团研究院有限公司 | Intermittent acidolysis method and device for titanium slag |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2441856A (en) * | 1942-08-01 | 1948-05-18 | Nat Lead Co | Cyclical process for the manufacture of titanium dioxide |
| US2770529A (en) * | 1955-08-24 | 1956-11-13 | Nat Lead Co | Method for preparing chlorination feed material |
| US3193376A (en) * | 1961-12-04 | 1965-07-06 | Wah Chang Corp | Beneficiation of ilmenite |
| US3368870A (en) * | 1963-12-06 | 1968-02-13 | Soloducha Nicolas | Method of producing titanium hydroxide and high grade pigments produced therefrom |
| US3428427A (en) * | 1965-06-24 | 1969-02-18 | Quebec Iron & Titanium Corp | Process for producing a product high in titanium dioxide content |
| BE754202A (en) * | 1969-07-31 | 1970-12-31 | Titangesellschaft Mbg | PROCESS FOR EXTRACTING IRON FROM TITANIUM ORE |
| DE1962155A1 (en) * | 1969-12-11 | 1971-06-16 | Sachtleben Ag | Process for the enrichment of titanium in titanium-containing minerals |
| ZA713018B (en) * | 1970-05-13 | 1972-01-26 | Montedison Spa | Process for the preparation of synthetic rutile starting from ilmenite |
| GB1312765A (en) * | 1971-03-12 | 1973-04-04 | British Titan Ltd | Benefication process for iron-containing titaniferous material |
-
1984
- 1984-05-17 DE DE19843418269 patent/DE3418269A1/en not_active Withdrawn
-
1985
- 1985-05-08 EP EP19850200719 patent/EP0164777B1/en not_active Expired - Lifetime
- 1985-05-08 DE DE8585200719T patent/DE3584473D1/en not_active Expired - Lifetime
- 1985-05-15 IN IN369/CAL/85A patent/IN163285B/en unknown
- 1985-05-16 CA CA000481721A patent/CA1234990A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7625536B2 (en) | 2005-10-18 | 2009-12-01 | Millennium Inorganic Chemicals, Inc. | Titaniferous ore beneficiation |
| CN113443649A (en) * | 2021-07-13 | 2021-09-28 | 攀钢集团研究院有限公司 | Intermittent acidolysis method and device for titanium slag |
| CN113443649B (en) * | 2021-07-13 | 2022-11-29 | 攀钢集团研究院有限公司 | Intermittent acidolysis method of titanium slag |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3584473D1 (en) | 1991-11-28 |
| IN163285B (en) | 1988-09-03 |
| DE3418269A1 (en) | 1985-11-21 |
| EP0164777A3 (en) | 1988-03-30 |
| EP0164777A2 (en) | 1985-12-18 |
| EP0164777B1 (en) | 1991-10-23 |
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