AU6641194A - Process for upgrading titaniferous materials - Google Patents
Process for upgrading titaniferous materialsInfo
- Publication number
- AU6641194A AU6641194A AU66411/94A AU6641194A AU6641194A AU 6641194 A AU6641194 A AU 6641194A AU 66411/94 A AU66411/94 A AU 66411/94A AU 6641194 A AU6641194 A AU 6641194A AU 6641194 A AU6641194 A AU 6641194A
- Authority
- AU
- Australia
- Prior art keywords
- process according
- titaniferous material
- leaching
- iii
- heat 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.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 53
- 230000008569 process Effects 0.000 title claims description 49
- 239000000463 material Substances 0.000 title claims description 45
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 45
- 238000002386 leaching Methods 0.000 claims description 33
- 239000012535 impurity Substances 0.000 claims description 31
- 229910052742 iron Inorganic materials 0.000 claims description 23
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 21
- 238000010438 heat treatment Methods 0.000 claims description 18
- 239000002253 acid Substances 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 6
- 239000011260 aqueous acid Substances 0.000 claims description 6
- 239000012633 leachable Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000001117 sulphuric acid Substances 0.000 claims description 6
- 235000011149 sulphuric acid Nutrition 0.000 claims description 6
- 239000010936 titanium Substances 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- 238000005273 aeration Methods 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 230000002378 acidificating effect Effects 0.000 claims description 3
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 2
- 238000009835 boiling Methods 0.000 claims description 2
- 238000002485 combustion reaction Methods 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- 238000010992 reflux Methods 0.000 claims description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims 3
- 239000000567 combustion gas Substances 0.000 claims 1
- 235000011121 sodium hydroxide Nutrition 0.000 claims 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 34
- 238000005660 chlorination reaction Methods 0.000 description 8
- YDZQQRWRVYGNER-UHFFFAOYSA-N iron;titanium;trihydrate Chemical compound O.O.O.[Ti].[Fe] YDZQQRWRVYGNER-UHFFFAOYSA-N 0.000 description 8
- 238000011282 treatment Methods 0.000 description 8
- 229910052500 inorganic mineral Inorganic materials 0.000 description 7
- 239000011707 mineral Substances 0.000 description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 239000004411 aluminium Substances 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 239000000571 coke Substances 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 5
- 238000000137 annealing Methods 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 239000000446 fuel Substances 0.000 description 5
- 229910052749 magnesium Inorganic materials 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 4
- 229910052776 Thorium Inorganic materials 0.000 description 4
- 239000003513 alkali Substances 0.000 description 4
- 239000000460 chlorine Substances 0.000 description 4
- 229910052801 chlorine Inorganic materials 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 239000004408 titanium dioxide Substances 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 4
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 3
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 3
- 235000013980 iron oxide Nutrition 0.000 description 3
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 238000007669 thermal treatment Methods 0.000 description 3
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052799 carbon Chemical group 0.000 description 2
- 239000003518 caustics Substances 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- -1 corrosion corrosion Substances 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001465 metallisation Methods 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 239000003209 petroleum derivative Substances 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 230000008570 general process Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004449 solid propellant Substances 0.000 description 1
- 150000004763 sulfides Chemical class 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Landscapes
- Crystals, And After-Treatments Of Crystals (AREA)
- Glass Compositions (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Description
PROCESS FOR UPGRADING TITANIFEROUS MATERIALS
This invention relates to the removal of impurities from naturally occurring and synthetic titaniferous materials. The invention is particularly suited to the production of feed material for industrial chlorination systems, as used in the production of titanium metal and titanium dioxide pigments.
Embodiments of the present invention have the common feature of annealing or other heat treatment of titaniferous materials which have been the product of high temperature reduction processing. The annealing or heat treatment is conducted in such a manner that impurities which have been converted by high temperature treatment into forms which can only be leached with difficulty are transformed into forms from which impurities can be leached with relative ease. The annealing or heat treatment is followed at some stage by cooling and aqueous leaching as steps in an integrated process. Additional steps may be employed as will be described below.
In industrial chlorination processes titanium dioxide bearing feedstocks are fed with coke to chlorinators of various designs (fluidised bed, shaft, molten salt) , operated to a maximum temperature in the range 700 -1200°C. The most common type of industrial chlorinator is of the fluidised bed design. Gaseous chlorine is passed through the titania and carbon bearing charge, converting titanium dioxide to titanium tetrachloride gas, which is then removed in the exit gas stream and condensed to liquid titanium tetrachloride for further purification and processing.
The chlorination process as conducted in industrial chlorinators is well suited to the conversion of pure titanium dioxide feedstocks to titanium tetrachloride.
However, most other inputs (i.e. impurities in feedstocks) cause difficulties which greatly complicate either the chlorination process itself or the subsequent stages of condensation and purification and disposal of waste. Table 1 provides an indication of the types of problems encountered. In addition, each unit of inputs which does not enter products contributes substantially to the generation of wastes for treatment and disposal. Some inputs (e.g. heavy metals, radioactives) result in waste classifications which may require specialist disposal in monitored repositories.
Preferred inputs to chlorination are therefore high grade materials, with the mineral rutile (at 95-96% Ti02) the most suitable of present feeds. Shortages of rutile have lead to the development of other feedstocks formed by upgrading naturally occurring ilmenite (at 40-60% Ti02)j
4/26944
TABLE 1
Elemental Chlorination Condensation Purification Input
Fe, Mn Consumes Solid/liquid chlorine, chlorides coke, foul increases gas ductwork, volume8 make sludges
Alkali & Defluidise alkali fluid beds earth due to liquid metals chlorides, consume chlorine,coke
Al Consumes Causes Causes chlorine, corrosion corrosion, coke makes sludges
Si Accumulates Can encourage May require in duct disti1lation chlorinator, blockage. from product reducing Condenses in campaign part with life. titanium
Consumes tetrachloride coke, chlorine v Must be removed, by chemical treatment and distillation
Th, Ra Accumulates in chlorinator brickwork, radioactive; causes disposal difficulties
such as titaniferous slag (approximately 86% Ti02) and synthetic rutile (variously 92-95% Ti02) . These upgrading processes have had iron removal as a primary focus, but have extended to removal of manganese and alkaline earth impurities, as well as some aluminium.
In the prior art, synthetic rutile has been formed from titaniferous minerals, e.g. ilmenite, via various techniques. According to the most commonly applied technique, as variously operated in Western Australia, the titaniferous mineral is reduced with coal or char in a rotary kiln, at temperatures in excess of 1100°C. In this process the iron content of the mineral is substantially metallised. Sulphur additions are also made to convert manganese impurities partially to sulphides. Following reduction the metallised product is cooled, separated from associated char, and then subjected to aqueous aeration for removal of virtually all contained metallic iron as a separable fine iron oxide. The titaniferous product of separation is treated with 2-5% aqueous sulphuric acid for dissolution of manganese and some residual iron. There is no substantial chemical removal of alkali or alkaline earths, aluminium, silicon, vanadium, or radionuclides in this process as disclosed or operated. Further, iron and manganese removal is incomplete. As a result of the high temperature treatment given the product of this process can only be leached for additional removal of impurities with difficulty.
Recent disclosures have provided a process which includes reduction to metallise ilmenite at lower temperatures and provides for leaching after aqueous aeration and iron oxide separation steps. According to these disclosures the process is effective in removing iron, manganese, alkali and alkaline earth impurities, a substantial proportion of aluminium inputs and some vanadium as well as thorium. The process may be operated
as a retrofit on existing kiln based installations. However, the process is ineffective in full vanadium removal and has little chemical impact on silicon. The leaching step of this process operated for some materials, notably those having higher than average magnesium levels, can require excessive acid strengths or pressure leach conditions, i.e. is conducted only with difficulty.
In another prior art invention relatively high degrees of removal of magnesium, manganese, iron and aluminium have been achieved. In one such process ilmenite is first thermally reduced to substantially complete reduction of its ferric oxide content (i.e. without substantial metallisation) , normally in a rotary kiln. The cooled, reduced product is then leached under 35 psi pressure at 140-150°C with excess 20% hydrochloric acid for removal of iron, manganesium, aluminium and manganese. The leach liquors are spray roasted for regeneration of hydrogen chloride which is absorbed into water and recirculated to the leaching step.
In other processes the ilmenite undergoes grain refinement by thermal oxidation followed by thermal reduction (either in a fluidised bed or a rotary kiln) . The cooled, reduced product is then subjected to atmospheric leaching with excess 20% hydrochloric acid, for removal of the deleterious impurities. Acid regeneration is also performed by spray roasting in this process.
In all of the above mentioned hydrochloric acid leaching based processes impurity removal is similar. Vanadium, aluminium and silicon removal is not fully effective. For those processes in which contained iron is not in part converted to metallic iron for ease of removal, acid consumption in the leach step is high, which can impact negatively on the economics of processing. Where iron is substantially converted to metallic iron under
higher temperature conditions of reduction with solid carbonaceous reductants, allowing good economics of iron removal for the majority of the contained iron, leaching of residual impurities becomes more difficult, requiring elevated pressures or very high strength acid.
In yet another process ilmenite is thermally reduced (without metallisation) with carbon in a rotary kiln, followed by cooling in a nonoxidising atmosphere. The cooled, reduced product is leached under 20 - 30 psi gauge pressure at 130°C with 10 - 60% (typically 18 - 25%) sulphuric acid, in the presence of a seed material which assists hydrolysis of dissolved titania, and consequently assists leaching of impurities. Hydrochloric acid usage in place of sulphuric acid has been claimed for this process. Under such circumstances similar impurity removal to that achieved with other hydrochloric acid based systems is to be expected. Where sulphuric acid is used radioactivity removal may not be complete.
A commonly adopted method for upgrading ilmenite to higher grade products is to smelt ilmenite with coke addition in an electric furnace, producing a molten titaniferous slag (for casting and crushing) and a pig iron product. Of the problem impurities only iron is removed in this manner, and then only incompletely as a result of compositional limitations of the process. The product so formed is not amenable to further upgrading by leaching at reasonable acid utilisations or without pressure leaching, i.e. it can only be upgraded by leaching with difficulty.
A wide range of potential feedstocks is available for upgrading to high titania content materials suited to chlorination. Examples of primary titania sources which cannot be satisfactorily upgraded by prior art processes for the purpose of producing a material suited to chlorination include hard rock (non detrital) ilmenites.
siliceous leucoxenes, many primary (unweathered) ilmenites and large anatase resources. Many such secondary sources (e.g. titania bearing slags) also exist.
For some upgraders of titania bearing feedstocks, in particular those who operate reduction in rotary kilns with solid carbonaceous reductants and those who operate smelting reduction, there is considerable incentive to continue to use installed capital equipment to achieve the present level of upgrading. The aim of further upgrading would then be best served by installing further plant and equipment as a retrofit to existing facilities. In each of these cases the existing high temperature processing operations as presently conducted will result in products which can only be leached for impurity removal with difficulty. This is especially the case for input materials having levels of magnesium which are higher than normal.
Clearly there is a considerable incentive to discover methods for converting titaniferous materials which have been produced by processes involving high temperature reduction processing into forms which can more readily be upgraded by acid leaching.
An object of the present invention is to provide processing steps which may be incorporated into more general processes for the upgrading of titaniferous materials, rendering such processes applicable to the treatment of a wider range of feeds and producing higher quality products than would otherwise be achievable.
Accordingly the present invention provides a process for removing impurities from a titaniferous material that has been subjected to thermal reduction, the process including the steps of:
(i) subjecting the thermally reduced titaniferous material to a secondary heat treatment to convert it to a leachable form in which impurities present therein are more readily leachable;
(ii) cooling the product of step (i) to form a cooled heat treated titaniferous material;
(iii) leaching the cooled heat treated titaniferous material in an aqueous acid solution that is capable of dissolving at least a portion of any impurities contained in the titaniferous material to form a leachate; and
(iv) separating the leachate from the titaniferous material to form a purified titaniferous material.
It has been discovered that the above processing steps enable the removal of iron, magnesium and other alkaline earths, alkali metals, manganese, thorium and radioactivity, which impurities are frequently completely removed only with difficulty from thermally processed titaniferous materials.
The secondary heat treatment step may be carried out in any suitable device. The advantages of temperature and atmosphere control offered by fluidised bed devices would recommend that fluidised beds, either stationary or circulating, be used, although rotary or grate kilning and shaft furnaces may also be used. The operating temperature or temperature cycle employed may be any such temperature or cycle which has the effects of rendering impurities more leachable under the atmosphere used. In general, the
combination of temperature or temperature cycle and atmosphere or atmosphere cycle should be such that the product of annealing or heat treatment has the majority of its contained iron in the ferrous or metallic state and only a small proportion of its contained titanium in other than the tetravalent state. Thermal processing atmosphere and temperature control for the secondary heat treatment may be achieved either by introduction of gases of controlled composition and temperature, e.g. by partial or complete combustion of fuels, or by direct addition of reductant and/or fuel and air to the chamber in the device in which the mineral is held. Fuel and/or reductant may be solid fuels such as coal or char, liquid fuels such as oil, or gaseous fuel/reductant such as natural gas, reformed natural gas, petroleum gas, reformed petroleum gas or suitable gaseous products from other processes or reactors.
The secondary heat treatment residence time will depend on the nature of the prior treatments, the feed, the operating temperature, and the processing atmosphere. Residence times of from 30 minutes to five hours have been effective.
The effect of secondary heat treatment on the oxidation state of the titaniferous material may be to oxidise or reduce the material or to have no appreciable effect. Under most circumstances it will be beneficial to slightly oxidise the material or to affect no net change in oxidation state overall, within the constraints defined above as to the composition of the heat treated material.
Cooling of the thermally treated material may be conducted in any manner which does not prove to be detrimental in practical terms to the ease with which the heat treated product can be acid leached for impurity removal. Cooling in a rotary cooler or a fluidised bed cooler will be effective. Direct quench cooling upon
discharge will also be effective under many circumstances.
The aqueous acid leaching step need not necessarily follow directly after the presently disclosed thermal processing step. For example an aeration step or a leach with non-acidic leachant, e.g. a caustic leach may precede the acid leach. Further, crushing/grinding of the thermally processed material to enhance subsequent leach performance may be undertaken.
The conditions necessary to conduct effective leaching will depend on the nature of the original feed and its treatment. Generally the product of annealing or heat treatment will be capable of being leached for at least partially effective removal of contained impurities in an hydrochloric acid leach liquor containing 10% HCl by weight under boiling reflux at atmospheric pressure. However, either milder or more aggresive leach conditions may be used, and any effective commercial acid may be applied. In particular, sulphuric acid and hydrochloric acid may be used for leaching. Pressure leaching, while generally unnecessary, may also be used.
Leaching may be conducted in any circuit configuration, including batch single or multiple stage leaching, continuous concurrent multistage leaching, or continuous countercurrent multistage leaching. For most circumstances two stage concurrent leaching will be most beneficial. Average residence time may vary from 30 minutes to 10 hours, depending on process conditions. Any leach vessel capable of providing adequate shear may be used. Simple stirred tank vessels are applicable.
At the conclusion of leaching the leach liquor may be separated from the mineral by any suitable means, including thickening, filtration and washing. The mineral product may then pass onto other steps in an integrated
process. For example, a further leach, for example a caustic leach, may follow the disclosed leaching step.
It is further herein disclosed that titaniferous materials which by virtue of prior treatments contain phases of the type "anosovite" or "pseudobrookite", i.e. generally contain a phase whose chemical composition can be summarised as "M305", and therefore are leached for removal of impurities contained within this phase only with difficulty, can be treated by the heat treatment step to produce preferentially the ilmenite-like impurity bearing phase whose chemical composition can be summarised as "M203". This latter phsae is much more readily leached for removal of impurities than the original impurity bearing phase. In particular, in the reduction of titaniferous materials containing elevated levels of magnesium to remove iron from titaniferous phases by the formation of metallic iron the "M305" phase cannot easily be avoided. Consequently acid leaching of such materials reduced in this manner will be most effective if a secondary heat treatment step can be successfully conducted, as is herein disclosed.
The present invention is described further by reference to the following examples.
Example 1:
This example illustrates the ineffectiveness of leaching of thermally processed materials in the absence of any secondary heat treatment.
A commercially available synthetic rutile product produced by the Becher process and containing elements other than Ti primarily in an M305 (pseudobrookite or anosovite) phase was leached under strong agitation with aqueous 20% HCl at 30% (by weight) solids density for 6
hours. At the end of this time the leach residue was separated from the leach liquors by filtration and washing.
Synthetic rutile feed and residue analyses are summarised in Table 1. While there has been some iron removal (presumably due to dissolution of attached iron oxides or metallic iron) there was no substantial removal of any other element.
Example 2:
A further sample of the synthetic rutile feed of Example 1 was subjected to fluidised bed roasting
(secondary thermal treatment) at 750°C with a mixture of hydrogen and carbon dioxide gases in the volume ratio 1:3 for 60 minutes, followed by cooling of the bed under nitrogen flushing. The cooled solids were then leached under identical conditions to those indicated in Example 1.
The residue analysis is provided in Table 2. There has been substantially greater removal of all impurities than was the case for acid leaching without the secondary thermal treatment. X-ray diffraction analysis indicated substantial conversion of the M305 to the metatitanate M203 by roasting. Roasting for complete conversion will thus result in even further removal of impurities such as thorium.
The above examples are only a broad indication of the wide range of possibilities in applying the disclosed processing steps in integrated processes for the upgrading of general titaniferous materials to high grade products.
Table 1: Acid Leaching of as Manufactured Becher Synthetic Rutile
Table 2: Acid Leaching of Becher Synthetic Rutile After Secondary Thermal Treatment
The above examples are only a broad indication of the wide range of possibilities in applying the disclosed processing steps in integrated processes for the upgrading of general titaniferous materials to high grade products.
Claims (13)
1. A process for removing impurities from a titaniferous material that has been subjected to thermal reduction, the process including the steps of:
(i) subjecting the thermally reduced titaniferous material to a secondary heat treatment to convert it to a leachable form in which impurities present therein are more readily leachable;
(ii) cooling the product of step (i) to form a cooled heat treated titaniferous material;
(iii) leaching the cooled heat treated titaniferous material in an aqueous acid solution that is capable of dissolving at least a portion of any impurities contained in the titaniferous material to form a leachate; and
(iv) separating the leachate from the titaniferous material to form a purified titaniferous material.
2. The process according to claim 1, wherein the majority of the contained iron in the product of step (i) is in the ferrous or metallic state.
3. The process according to claim 1 or claim
2, wherein the majority of the contained titanium in the product of step (i) is in the tetravalent state.
. The process according to any one of the
preceding claims comprising, selecting the conditions of the secondary heat treatment step (i) to convert M305 phase titaniferous material into the more readily acid leachable M203 phase.
5. The process according to any one of the preceding claims, wherein the temperature of the heat treatment step (i) is in the range of 700-900°C.
6. The process according to any one of the preceding claims, wherein the time of the heat treatment is between 30 minutes and 5 hours.
7. The process according to any one of the preceding claims, wherein the heat treatment step (i) comprises contacting the thermally reduced titaniferous material with gases of controlled composition and temperature.
8. The process according to claim 7, wherein the gases comprise combustion gases produced by incomplete combustion.
9. The process according to any one of the preceding claims, wherein the aqueous acid solution of step
(iii) comprises hydrochloric or sulphuric acid.
10. The process according to claim 9, wherein the aqueous acid solution of step (iii) comprises HCl leach liquor containing 10% HCl by weight under boiling reflux at atmosphere pressure.
11. The process according to any one of the preceding claims, wherein the average residence time of the cooled heat treated titaniferous material in the aqueous acid solution in step (iii) is between 30 minutes and 10 hours.
12. The process according to any one of the preceding claims further comprising, the step of subjecting the cooled heat treated titaniferous material of step (ii) to aeration or leaching with a non-acidic leachant prior to acid leaching in step (iii) .
13. The process defined in claim 12, wherein the non-acidic leachant comprises caustic soda.
1 . The process according to any one of the preceding claims further comprising, the step of crushing or grinding the cooled heat treated titaniferous material of step (ii) prior to acid leaching in step (iii) .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU66411/94A AU687054B2 (en) | 1993-05-07 | 1994-05-09 | Process for upgrading titaniferous materials |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPL867993 | 1993-05-07 | ||
AUPL8679 | 1993-05-07 | ||
PCT/AU1994/000241 WO1994026944A1 (en) | 1993-05-07 | 1994-05-09 | Process for upgrading titaniferous materials |
AU66411/94A AU687054B2 (en) | 1993-05-07 | 1994-05-09 | Process for upgrading titaniferous materials |
Publications (2)
Publication Number | Publication Date |
---|---|
AU6641194A true AU6641194A (en) | 1994-12-12 |
AU687054B2 AU687054B2 (en) | 1998-02-19 |
Family
ID=25635104
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU66411/94A Ceased AU687054B2 (en) | 1993-05-07 | 1994-05-09 | Process for upgrading titaniferous materials |
Country Status (1)
Country | Link |
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AU (1) | AU687054B2 (en) |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CZ22695A3 (en) * | 1992-07-31 | 1996-01-17 | Rgc Mineral Sands Ltd | Process of treating titanium-containing materials |
AU5249493A (en) * | 1992-12-16 | 1994-06-30 | Rgc Mineral Sands Limited | Treatment of titaniferous materials |
-
1994
- 1994-05-09 AU AU66411/94A patent/AU687054B2/en not_active Ceased
Also Published As
Publication number | Publication date |
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AU687054B2 (en) | 1998-02-19 |
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