AU2002354885A1 - Recovery of titanium from titanium bearing materials - Google Patents
Recovery of titanium from titanium bearing materialsInfo
- Publication number
- AU2002354885A1 AU2002354885A1 AU2002354885A AU2002354885A AU2002354885A1 AU 2002354885 A1 AU2002354885 A1 AU 2002354885A1 AU 2002354885 A AU2002354885 A AU 2002354885A AU 2002354885 A AU2002354885 A AU 2002354885A AU 2002354885 A1 AU2002354885 A1 AU 2002354885A1
- Authority
- AU
- Australia
- Prior art keywords
- solution
- titanium dioxide
- sulphate
- tio
- 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.)
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Description
RECOVERY OF TITANIUM FROM TITANIUM BEARING MATERIALS
BACKGROUND OF THE INVENTION
THIS invention relates to the recovery of titanium from titanium bearing materials, and in particular to a method of recovering titanium dioxide or titanium metal from a titanium dioxide bearing material.
Highveld Steel and Vanadium Corporation is a large manufacturer of steel using its own unique steel manufacturing process. The slag produced in this steel manufacturing process is rich in titanium dioxide, typically in amounts of 22 to 32% of the slag material.
Pure titanium dioxide is white in colour and is, therefore, a valuable pigment used in many applications such as the production of paints, paper, cement, polymers and the like. The slag produced in the Highveld Steel manufacturing process is an ideal source of titanium dioxide for this purpose.
SUMMARY OF THE INVENTION
A method of recovering titanium dioxide from a raw material containing the titanium dioxide and aluminium, typically as its oxide, comprises the steps of:
a) grinding the titanium dioxide bearing material to form a particulate raw feed mateπal;
b) contacting the particulate raw feed material with a predetermined amount of sulphuric acid in a reaction vessel and raising the temperature in the reaction vessel to a predetermined temperature at which a reaction takes place to produce a cake material containing titanyl sulphate;
c) contacting the cake material with a sufficient quantity of water, and optionally recovered process acid, to dissolve the cake material, which contains the titanyl sulphate;
d) filtering the resultant suspension and collecting the solution containing the titanyl sulphate and, if present, optionally treating the solution to remove iron and/or calcium;
e) contacting the titanyl sulphate containing solution with ammonium sulphate to produce aluminium ammonium sulphate in the solution;
f) precipitating the aluminium ammonium sulphate out of the solution and separating it from the titanyl sulphate containing solution;
g) hydrolysing the titanyl sulphate containing solution by contacting the solution with water, which has first been seeded with an appropriate amount of rutile and heated, or a
portion of previously hydrolysed solution containing hydrated titanium dioxide, and heating the solution to boiling point to precipitate out hydrated titanium dioxide;
h) washing the hydrolysate with an ammonium solution to remove residual sulphates as ammonium sulphates followed by filtering off the hydrated titanium dioxide; or
i) filtering the hydrolysate followed by washing with sodium hydroxide, ammonium hydroxide, water, phosphoric acid and/or diluted sulphuric acid; and
j) calcining the hydrolysate to drive off any residual acid and water of crystallisation to produce titanium dioxide.
The raw material typically also contains vanadium, calcium and/or iron, typically as their oxides.
The vanadium is typically removed as VOSO4 in the solution remaining in step g).
In this regard, the Ti3+ (as TiO2) in the hydrolytic solution is preferably kept at a concentration of 3 to 4g/t Ti3+ to prevent hydrolysis of the VOSO4 and incorporation into the hydrated TiO2 product.
The insoluble solid residue produced in step c) is preferably separated from the solution by clarification, typically with the addition of gellatene and/or glue, dextrine, tannic acid, AMPAM or other appropriate clarifier, before the suspension is filtered in step d).
The hydrolysis step g) is preferably carried out in the absence of a prior crystallisation and vacuum concentration step having taken place.
The cake mateπal of step b) is preferably left to mature for about 2 to 3 hours at a temperature of about 190°C to 250°C before being dissolved in step c).
In step c), air is preferably introduced with the water, and optionally recovered process acid, in order to assist with agitation to dissolve the cake.
The air is preferably cold air to control the reaction temperature below about 75°C, typically 70 to 75°C, in order to prevent premature crystallisation of TiO2.
The slag in step a) is preferably ground to form a particulate material in which at least 80% of the particles are able to pass through a 45 micron mesh.
The reaction of the sulphuric acid solution and particulate feed material in step b) typically takes place in a fusion reactor, which may be a batch or continuous fusion reactor.
The temperature is preferably raised in the fusion reactor by introducing pre-heated air into the reaction vessel.
After the desired amount of water has been introduced, air and mechanical agitation is used to break the cake into a homogenous suspension.
The calcium is typically removed as calcium sulphate, typically during the filtration step d).
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawing, which is a schematic flow
diagram of a preferred embodiment of a method of recovering titanium dioxide according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The present invention is directed at a so-called sulphating process for recovering titanium, in particular titanium dioxide, from a titanium bearing material, in particular a slag produced in a steel manufacturing process containing titanium dioxide and aluminium, and typically also vanadium, calcium, and/or iron, typically as their oxides.
The process of the invention, as set out in the accompanying drawing, is particularly suited for recovering TiO2 from a slag as set out below.
Total TiO2 24 - 30%
FeO 2 - 8%
Fe2O3 2 - 8%
CaO 14 - 16%
MgO 12 - 15%
SiO2 20 - 25%
AI2O3 12 - 14%
V2O5 0.2 - 1%
MnO 0.2 - 1%
S 0.01 - 0.2%
Na2O 0 - 0.2%
P2O5 0.01 %
H2O 0.06%
The titanium slag (elkem slag) available is dried as needed and ground to a uniform fine particle size of less than 45μm. The pulverized slag is mixed with approximately 1.3 parts by weight of 93% to 98% sulphuric acid and stirred with compressed air in a reactor vessel. The mixture is heated with pre-heated air in the reactor vessel. At about 100°C the exothermic
reaction starts, increasing rapidly when the temperature reaches 180°C, and the slag is converted into a solid mass composed of soluble titanium, aluminium, vanadium and iron sulphates. The use of heated air instead of heated steam has been found to be preferable. The reason for this is that the Highveld Steel slag used in the process has free iron present, in an amount of about 4%, in the ferrous state. Accordingly, it is undesirable to have water in the fusion reaction as it would transform the free iron to the Fe+++ state. In addition, the presence of oxygen in the heated air assists in the recovery of the titanium by converting Ti+++ to Ti++++.
Cold air is then blown through the cake for about 4 hours after the reaction is completed to produce a porous cake. The cake so produced is left to mature at a temperature of about 190 to 250°C for about 2 to 3 hours.
The reaction cake is then digested in water, and optionally recovered process acid, in a ratio of water to solid of about 3:1 in order to dissolve the desired titanium compounds. During the introduction of water, air is introduced simultaneously to assist with agitation, as mechanical agitation would not at this stage be effective due to the solid cake formed. During the introduction of air and water an exothermic reaction takes place. As it is important for the reaction temperature to be controlled below 75°C, in order to avoid premature crystallisation of the TiO2, proper flow control of the cold air into the reactor vessel is maintained. After the desired amount of water has been introduced, air and mechanical agitation is used to break the cake into a homogeneous suspension. The appropriate time to achieve the suspension is in the order of 4 hours, but visible inspection will indicate when this has been achieved.
Some of the titanium compounds which are believed to go into solution when digesting the cake with water include:
TiO2.xH2O
TiOSO4.H2O
TiOSO4.2H2O
TiSO4.H2SO4.2H2O
TiSO4.H2SO4.H2O Ti(SO4)2.
Where ilmenite is used as a raw material, the solution typically contains trivalent or "ferric" iron. This is reduced to the divalent or "ferrous" form with scrap iron as reducing agent. This step is not required in the case of the Highveld Steel slag as the iron in the slag is already in the "ferrous" state.
Following leaching the insoluble solid residue is separated from the resulting solution by clarification. The elkem slag contains impurities, some of which easily form colloidal solutions, such as SiO2 and AI2O3. Most of the hydrated silica is destroyed under the high reaction temperature. The insoluble solids can easily be separated from the leaching solution by clarification with the addition of gellatene and/or glue, dextrine and tannic acid. AMPAM clarificant solution can also be used.
The suspension so obtained is filtered through a filter system, typically using large settling tanks. The filtrate consists mainly of calcium sulphate CaSO4 and residue. The residue is then washed with water for disposal. Alternatively, the CaSO4 residue can be treated to recover H2SO4.
A very dense yellow solution is obtained after filtering, which is rich in peroxide TiO3.2H2O. By way of information, the peroxide is an oxidising substance which is unstable in the presence of water and is much more soluble than TiO2 or TiO2.H2O. It dissolves in acid solutions with the formation of yellow to red pertitanyl ions (TiO2 ++). In alkaline solutions, it forms titanate ions (HTiO3 ") and/or colourless pertitanate ions (HTiO4 " and TiO4 ~). The solubility of the peroxide is around 1g.mol/l at a pH of 0.5 (acid medium) and at a pH of 12 (alkaline medium). By the action of hydrogen peroxide on very acid solutions of tri- or tetravalent titanium, a solution of peroxidized TiO2 ++ ions is obtained, which deposits as a precipitate of peroxide, TiO3.2H2O, upon increasing the pH.
The clarified titanyl sulphate solution contains approximately 100 gpl TiO2 and 15 gpl AI2(SO4)3.
If the solution is concentrated to about 200 gpl TiO2, the aluminium sulphate will be precipitated as a crystalline solid at room temperature, and the solution will become an "unflowed solid". Therefore the aluminium sulphate must be removed from the clarified solution before concentration. The ammonium sulphate is added to the solution, which then reacts with the aluminium sulphate in it as follows:
AI2(SO4)3 + (NH4)2SO4 + 12H2O ► NH4AI(SO4)2.12H2O
After reaction, the aluminium ammonium sulphate is precipitated in crystalline solid form and separated from the solution.
The solution is then filtered to remove traces of insoluble materials.
During the hydrolysis step, the titanium solution is transformed into a white titanium oxyhydrate slurry. The steps that have gone before are fundamental in preparing the titanium compounds for hydrolysis. One step which is not required when using Highveld slag is crystallization and vacuum concentration. Thus, hydrolysis is carried out by contacting the titanyl sulphate containing solution with heated water which has been seeded with nucleating or seeding agents, in particular nuclei rutile, and then boiled.
The formation of titanyl hydroxide proceeds according to the following reactions:
Ti++++ + 2OH" ► TiO++ + H2O and
TiO++ + 2OH" ► TiO(OH)2
To increase the rate of thermal hydrolysis of sulphate solutions at atmospheric pressure and at the same time obtain products of pigment grade, nucleating or seeding agents are added. Normally only 1% nuclei or seed agent is required.
The composition, purity, and physical properties of hydrolytically precipitated titanium dioxide depend to a large extent upon the conditions under which the decomposition takes place, such as composition of the solution employed, temperature, and duration of boiling. In the commonly employed processes, large changes in the concentration of the solution would take place as the hydrolysate is formed and an equivalent amount of acid is liberated. Thus the formation of titanic acid will take place under entirely different conditions at the beginning and at the end of the operation.
To overcome this effect, a titanium-rich solution is prepared from the slag, transferred into a precipitation vessel and heated until practically complete hydrolysis has taken place. Four fifths of the liquor is then removed. To the remaining one fifth, still at the precipitation temperature, fresh pregnant solution is added at such a rate as to secure a practically constant concentration of dissolved titanium until the vessel is filled. Heating is continued throughout the process. The supply of solution is then interrupted, and four fifths of the liquor is again removed. The operation is repeated as often as is necessary. The above process only requires initial introduction of nuclei or seeding agents, thereafter the one fifth liquor contains enough nuclei seeding agents to initiate the hydrolysis reaction. The total cycle time of the exercise is between 3 and 6 hours.
The titanyl sulphate solution treated in the above hydrolysis step contains about 1% V2O5 and the weight ratio of vanadium to titanium (as V2O5 / TiO2) is about 1%. The behavior of titanyl sulphate and vanadium sulphate are different. If the pH value of the solution is about 3, the vanadium sulphate will be hydrolyzed. However, if the hydrolytic solution has about 3 to 4 gpl Ti3+ (as TiO2) and about 20% of free sulphuric acid, the vanadium sulphate does not hydrolyse.
Test results of hydrolysis showed that about 65% of the vanadium in the hydrolytic solution remained in the mother solution, the remainder being precipitated with the hydrated TiO2. During the washing process, the pH value of the washing water increases. The vanadium sulphate absorbed
into the surface of hydrated TiO2 will be hydrolyzed and incorporated into the hydrated TiO2. In order to prevent vanadium from going into the product, the Ti3+ content of the hydrolytic solution is controlled between 3 to 4 gpl (as TiO2).
The TiO2.xH2O is removed by means of filtering through a filtering system. The hydrolysate is then washed with either sodium hydroxide, ammonium hydroxide, water, phosphoric acid or dilute sulphuric acid to improve the properties of the titanium white.
The vanadium solution can be heated with a 25% NH3 solution, crystallised and filtered to recover the vanadium and (NH4)2SO .
The main reason for washing the hydrolysate is to neutralize the liquor and to improve the crystal properties. Conditioning agents such as dilute acids and zinc or aluminium powder or a powerful non-metallic reducing agent or phosphoric acid or an alkaline metal could also be introduced during this washing stage, to ensure the formation of the rutile structure during the calcination process that follows.
The thoroughly purified and washed hydrolysate obtained by the thermal hydrolysis of titanium salt solutions is an amorphous hydrous oxide which still contains impurities as chemi-adsorbed acid. In addition, it is too finegrained and almost amorphous, which is undesirable for pigment grade TiO2. In the production of pigment grade TiO2, accordingly, a calcination step is necessary to drive off the water and residual acid and at the same time convert the titanium dioxide to the crystalline form of a required particle size. At the same time, desired pigmentary properties are developed.
Amorphous titanic oxide or hydroxide (TiO.xH2O.SO3), such as is obtained from the sulphate solution, is converted to the crypto crystalline modification of pigment grade TiO2 by calcination at 950°C for 1 hour.
The calcined TiO2 is finally ground to 325 mesh powder having a purity of greater than 99.9%.
Claims (12)
1. A method of recovering titanium dioxide from a raw material containing the titanium dioxide and aluminium, comprises the steps of:
a) grinding the titanium dioxide bearing material to form a particulate raw feed material;
b) contacting the particulate raw feed material with a predetermined amount of sulphuric acid in a reaction vessel and raising the temperature in the reaction vessel to a predetermined temperature at which a reaction takes place to produce a cake material containing titanyl sulphate;
c) contacting the cake material with a sufficient quantity of water, and optionally recovered process acid, to dissolve the cake material, which contains the titanyl sulphate;
d) filtering the resultant suspension and collecting the solution containing the titanyl sulphate and, if present, optionally treating the solution to remove iron and/or calcium;
e) contacting the titanyl sulphate containing solution with ammonium sulphate to produce aluminium ammonium sulphate in the solution;
f) precipitating the aluminium ammonium sulphate out of the solution and separating it from the titanyl sulphate containing solution;
g) hydrolysing the titanyl sulphate containing solution by contacting the solution with water, which has first been seeded with an appropriate amount of rutile and heated, or a portion of previously hydrolysed solution containing hydrated titanium dioxide, and heating the solution to boiling point to precipitate out hydrated titanium dioxide;
h) washing the hydrolysate with an ammonium solution to remove residual sulphates as ammonium sulphates followed by filtering off the hydrated titanium dioxide; or
i) filtering the hydrolysate followed by washing with sodium hydroxide, ammonium hydroxide, water, phosphoric acid and/or diluted sulphuric acid; and
j) calcining the hydrolysate to drive off any residual acid and water of crystallisation to produce titanium dioxide.
2. A process according to claim 1 , wherein the raw material contains iron and/or calcium, which is/are removed from the titanyl sulphate solution in step d).
3. A method according to claim 1 or claim 2, wherein the raw material contains vanadium, which is removed as VOSO4 in the solution remaining in step g).
4. A method according to claim 3, wherein the Ti3+ (as TiO2) in the hydrolytic solution is kept at a concentration of 3 to 4g/ϋ Ti3+ to prevent hydrolysis of the VOSO and incorporation into the hydrated TiO2 product.
5. A process according to any one of claims 1 to 5, wherein the aluminium and the vanadium, calcium and iron, when present, are present as their oxides.
6. A method according to claim 1 , wherein the insoluble solid residue produced in step c) is separated from the solution by clarification, before the suspension is filtered in step d).
7. A method according to claim 6, wherein the clarification step is carried out with the addition of gellatene and/or glue, dextrine, tannic acid, AMPAM or other appropriate clarifier.
8. A method according to claim 1 , wherein the hydrolysis step g) is carried out in the absence of a prior crystallisation and vacuum concentration step having taken place.
9. A method according to claim 1 , wherein the cake material of step b) is left to mature for about 2 to 3 hours at a temperature of about 190°C to 250°C before being dissolved in step c).
10. A method according to claim 1 , wherein in step c), air is introduced with the water, and optionally recovered process acid, in order to assist with agitation to dissolve the cake.
11. A method according to claim 10, wherein the air is cold air to control the reaction temperature below about 75°C, in order to prevent premature crystallisation of TiO2.
12. A method according to claim 11 , wherein the reaction temperature is controlled between 70 and 75°C.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA200105826 | 2001-07-16 | ||
ZA2001/5826 | 2001-07-16 | ||
PCT/IB2002/002768 WO2003008335A1 (en) | 2001-07-16 | 2002-07-16 | Recovery of titanium from titanium bearing materials |
Publications (2)
Publication Number | Publication Date |
---|---|
AU2002354885A1 true AU2002354885A1 (en) | 2003-05-22 |
AU2002354885B2 AU2002354885B2 (en) | 2007-02-01 |
Family
ID=25589242
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU2002354885A Ceased AU2002354885B2 (en) | 2001-07-16 | 2002-07-16 | Recovery of titanium from titanium bearing materials |
Country Status (9)
Country | Link |
---|---|
US (1) | US7258847B2 (en) |
EP (1) | EP1409410B1 (en) |
CN (1) | CN100441513C (en) |
AT (1) | ATE284843T1 (en) |
AU (1) | AU2002354885B2 (en) |
BR (1) | BR0211945A (en) |
CA (1) | CA2457837A1 (en) |
DE (1) | DE60202295T2 (en) |
WO (1) | WO2003008335A1 (en) |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2454173T3 (en) * | 2006-09-06 | 2014-04-09 | Bhp Billiton Innovation Pty Ltd | Sulfate process |
CN102139424A (en) * | 2011-03-21 | 2011-08-03 | 北京工业大学 | Gas-shielded flux-cored wire with recyclable welding slag |
US10815549B2 (en) * | 2014-04-17 | 2020-10-27 | AluChem Companies, Inc. | Method for the purification of alumina |
EA035062B1 (en) | 2014-07-08 | 2020-04-23 | Авертана Лимитед | Extraction of products from titanium-bearing minerals |
WO2016112432A1 (en) * | 2015-01-13 | 2016-07-21 | Iluka Resources Limited | Beneficiation of titanium bearing materials |
CN107540013B (en) * | 2016-06-27 | 2019-06-07 | 中国科学院金属研究所 | A kind of preparation method for the titania nanoparticles that high visible absorbs |
WO2018152628A1 (en) * | 2017-02-24 | 2018-08-30 | Vanadiumcorp Resources Inc. | Metallurgical and chemical processes for recovering vanadium and iron values from vanadiferous titanomagnetite and vanadiferous feedstocks |
CN106884097B (en) * | 2017-04-08 | 2018-07-06 | 广西凤山县五福矿业发展有限公司 | A kind of method that titanium is enriched with from the low molten aluminium slag of iron aluminium concentrate |
CN108277349A (en) * | 2018-02-01 | 2018-07-13 | 燕山大学 | A kind of selective reaction separation of titanium aluminium laminar composite and recovery method |
EP3894607A4 (en) * | 2018-12-14 | 2022-12-21 | Avertana Limited | Methods of extraction of products from titanium-bearing materials |
CN112299475A (en) * | 2020-11-03 | 2021-02-02 | 安徽迪诺环保新材料科技有限公司 | Nanometer titanium dioxide for ultra-pure high-specific-surface-area denitration and preparation method thereof |
CN113213529B (en) * | 2021-05-26 | 2022-08-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for producing titanium dioxide by sulfuric acid process and recycling metatitanic acid in titanium dioxide waste acid |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2837426A (en) * | 1955-01-31 | 1958-06-03 | Nat Distillers Chem Corp | Cyclic process for the manufacture of titanium-aluminum alloys and regeneration of intermediates thereof |
GB2109356A (en) * | 1981-10-21 | 1983-06-02 | Akad Gorniczo Hutnicza | Method of isolating alkali metal and titanium values from red slime and similar materials |
US5030439A (en) * | 1989-10-17 | 1991-07-09 | Kerr-Mcgee Chemical Corporation | Method for producing particulate titanium oxides |
WO1996010096A1 (en) * | 1994-09-29 | 1996-04-04 | Tioxide Australia Pty. Ltd. | Process and solution for extracting metal |
-
2002
- 2002-07-16 BR BR0211945-5A patent/BR0211945A/en not_active Application Discontinuation
- 2002-07-16 DE DE60202295T patent/DE60202295T2/en not_active Expired - Fee Related
- 2002-07-16 EP EP02751459A patent/EP1409410B1/en not_active Expired - Lifetime
- 2002-07-16 CN CNB028180941A patent/CN100441513C/en not_active Expired - Fee Related
- 2002-07-16 WO PCT/IB2002/002768 patent/WO2003008335A1/en not_active Application Discontinuation
- 2002-07-16 CA CA002457837A patent/CA2457837A1/en not_active Abandoned
- 2002-07-16 AT AT02751459T patent/ATE284843T1/en not_active IP Right Cessation
- 2002-07-16 AU AU2002354885A patent/AU2002354885B2/en not_active Ceased
- 2002-07-16 US US10/484,240 patent/US7258847B2/en not_active Expired - Fee Related
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