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
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
  • C22B1/24—Binding; Briquetting ; Granulating
  • C22B1/242—Binding; Briquetting ; Granulating with binders
  • C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
• • 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
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/02—Roasting processes
• • 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
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
  • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
  • C22B3/10—Hydrochloric acid, other halogenated acids or salts thereof
• • 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
• • 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
  • C22B34/1209—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 dry processes, e.g. with selective chlorination of iron or with formation of a titanium bearing slag
• • 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

Definitions

• This invention relates to the removal of impurities from naturally occurring and synthetic titaniferous materials.
• the invention is particularly suited to the enhancement of titaniferous materials used in the production of titanium metal and titanium dioxide pigments by means of industrial chlorination systems.
• Embodiments of the present invention have the common feature of roasting of titaniferous materials in the presence of additives and at temperatures which encourage the formation of a liquid oxide or glassy phase, 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.
• 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 700-1200C.
• chlorinators of various designs (fluidised bed, shaft, molten salt), operated to a maximum temperature in the range 700-1200C.
• 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.
• Preferred inputs to chlorination are therefore high grade materials, with the mineral rutile (at 95-96% TiO 2 ) the most suitable of present feeds.
• Shortages of rutile have led to the development of other feedstocks formed by upgrading naturally occurring ilmenite (at 40-60% TiO 2 ), such as titaniferous slag (approximately 86% TiO 2 ) and synthetic rutile (variously 92-95% TiO 2 ).
• These upgrading processes have had iron removal as a primary focus, but have extended to removal of magnesium, manganese and alkali earth impurities, as well as some aluminium.
• Elemental Input Chlorination Condensation Purification Fe, Mn Consumes Solid/liquid chlorine, chlorides coke, foul increases ductwork, gas volumes make sludges Alkali & Defluidise alkali fluid beds earth due to metals liquid chlorides, consume chlorine, coke Al Consumes Causes Causes chlorine, corrosion corrosion, coke makes sludges Si Accumulates Can May require in encourage distillation chlorinator, duct from product reducing blockage.
• titaniferous minerals e.g. ilmenite
• the titaniferous mineral is reduced with coal or char in a rotary kiln, at temperatures in excess of 1100 C.
• the iron content of the mineral is substantially metallised.
• Sulphur additions are also made to convert manganese impurities partially to sulphides.
• 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.
• aqueous sulphuric acid for dissolution of manganese and some residual iron.
• Recent disclosures have provided a process which operates reduction at lower temperatures and provides for hydrochloric acid leaching after the 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 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.
• ilmenite is thermally reduced (without metallisation) with carbon in a rotary kiln, followed by cooling in a non-oxidising 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 will not be complete.
• a commonly adopted method for upgrading of ilmenite to higher grade products is to smelt ilmenite at temperatures in excess of 1500° C. with coke addition in an electric furnace, producing a molten titaniferous slag (for casting and crushing) and a pig iron product.
• molten titaniferous slag for casting and crushing
• 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.
• a titaniferous ore is treated by alternate leaching with an aqueous solution of alkali metal compound and an aqueous solution of a mineral acid (U.S. Pat. No. 5,085,837).
• the process is specifically limited to ores and concentrates and does not contemplate prior processing aimed at artificially altering phase structures. Consequently the process requires the application of excessive reagent and harsh processing conditions to be even partially effective and is unlikely to be economically implemented to produce a feedstock for the chloride pigment process.
• 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 purposes of production of 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.
• the present invention provides a combination of 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.
• the present invention provides a process for upgrading a titaniferous material by removal of impurities which process includes the steps of:
• step (ii) cooling the product of step (i) to form a solidified material comprising the titaniferous phase and an impurity bearing phase at a rate sufficient to ensure the susceptibility of the impurity bearing phase to leaching in either an acid or alkaline leachant;
• the process of the invention can remove iron, magnesium and other alkaline earths, alkalis, manganese, silica, phosphorus, alumina, vanadium, rare earths, thorium and other radioactive elements, which impurities form an almost comprehensive list of impurities in titaniferous mineral sources. From most materials a product purity of greater than 96% TiO 2 can be obtained.
• Compounds added to the titaniferous material may be mixed therewith by any means ranging from direct mixing of additives prior to charging to thermal treatment to more complex feed preparations such as the formation of agglomerates or nodules of mixed products, to briquette production from feeds and additives.
• Many additives will be effective.
• sodium, potassium, lithium, phosphorus, silicon and boron compounds and minerals e.g. borax, trona and other alkali metal carbonates, spodumene, caustic soda
• Additives may be incorporated individually or in combination with other additives.
• the formation of a glassy phase by addition of alkali compounds can be achieved without the formation of alkali titanate phases, reduced alkali titanate phases (e.g. NaTiO 2 -compounds and solid solutions) or alkali ferric titanate phases (e.g. Na(Fe, Al)O 2 —TiO 2 phases known as “bronzes”) in roasting.
• alkali titanate phases e.g. NaTiO 2 -compounds and solid solutions
• alkali ferric titanate phases e.g. Na(Fe, Al)O 2 —TiO 2 phases known as “bronzes”
• Thermal processing may be carried out in any suitable device.
• the production of liquid phases would recommend rotary or grate kilning, but shaft furnaces may also be used and it has been found that fluidised beds can be used under some circumstances.
• Any gaseous atmosphere conditions may be used, from fully oxidising to strongly reducing.
• the thermal processing atmosphere should be chosen to most suit other steps in integrated processing. Reducing conditions may be achieved where desired by either the use of a sub stoichiometric firing flame or the addition of coal, char or coke with the thermal processing charge.
• Thermal processing residence time at temperature will depend on the nature of the additives and the feed, as well as the operating temperature. Residence times of from 5 minutes to five hours have been effective, allowing thermal processing residence times to be set to most suit other requirements in integrated processing.
• the level of additive used and the conditions applied in thermal processing should be such that glassy phase formation does not exceed the limitations set by materials handling constraints in the thermal processing step. For example, where glassy phase formation exceeds about 15% by volume of the roasted material it must be anticipated that accretion and bed fusion problems will occur.
• Cooling of the thermally treated material should be conducted in such a manner as to limit the reversion of the glassy phase to crystalline phases, i.e. should be at a sufficient rate to a temperature at which the liquid glass solidifies as to ensure the formation of at least a portion of solid glass rather than complete formation of crystalline products.
• cooling should be conducted under an environment appropriate to the conditions of thermal treatment (i.e. reduction processing will require cooling in an oxygen free environment).
• the aqueous leaching step need not necessarily follow directly after the presently disclosed thermal processing step.
• the thermal processing step may be optionally followed by a reduction step prior to aqueous leaching. 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 the additives. For example, addition of soda ash and borax to siliceous leucoxene in accordance with the present disclosure will result in a product which can be leached in sodium silicate solution formed directly from the thermally treated material; the active leachant in this case is simply water. In other cases up to 100 gpL caustic soda solution or acid will be an effective leachant. Leaching will generally benefit substantially by use of high temperature (e.g. 80° C. or above), although it has not been necessary to use pressure leaching to achieve effective conditions. Nevertheless it is presently disclosed that pressure leaching can be effectively and successfully applied. Lower temperatures can also be used, although with penalties in process kinetics.
• high temperature e.g. 80° C. or above
• Leaching may be conducted in any circuit configuration, including batch single or multiple stage leaching, continuous cocurrent multistage leaching, or continuous countercurrent multistage leaching. For most circumstances two stage cocurrent 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.
• the leach liquor may be separated from the mineral by any suitable means, including thickening, filtration and washing.
• the mineral product may then pass on to other steps in an integrated process.
• a further acid leach may follow the disclosed leaching step, particularly where the titaniferous feed has a content of alkalis or alkaline earths.
• reagent regeneration e.g. caustic regeneration, hydrochloric acid regeneration, sulphuric acid regeneration
• a physical separation step may be employed at any stage (e.g. a final magnetic separation to remove grains containing iron, such as chromite).
• Sodium carbonate addition corresponding to 4.25% Na 2 O by weight, was made to a titania concentrate whose composition is given in Table 1.
• the mixture was homogenised and pelletised, and the pellets were heated in air to 1000° C. for 4 hours.
• the thus roasted pellets were quenched in liquid nitrogen and then crushed to pass a screen of 200 microns aperture.
• Sodium silicate solution was used to simulate leaching using water as leachant under conditions where the leach liquors are recycled to leaching after solid/liquid separation).
• the original concentrate was known to contain silica primarily as quartz inclusions in titanate grains.
• X-ray diffraction analysis after roasting indicated extinction of all crystalline phases containing silica.
• a glassy phase containing 16% Na 2 O, 46% SiO 2 , 9% Al 2 O 3 , 26% TiO 2 and 3% Fe 2 O 3 was identified in the roasted material by electron microscopy.
• Sodium titanates and sodium iron titanium bronze were also identified (along with rutile) by these techniques, indicating that conditions were not optimised.
• titania concentrates of the composition given in Table 2 were used as titaniferous material for treatment.
• Two batches of band pressed pellets were prepared as follows. A 100 g sample of the concentrates (previously ground to passing a screen aperture of 30 microns) was blended in each case with 1.1% of the appropriate additive or additive mixture and the resulting blends were pressed into pellets. The first batch was prepared with 1.1 wt % of anhydrous borax addition while the second batch was prepared with addition of 1.1 wt % of 1:1 Na 2 B 4 O 7 :Na 2 O.
• Each batch of pellets was roasted for two hours in a 7:1 H 2 /CO 2 atmosphere at 1000° C. and then removed to cool quickly in the same atmosphere.
• the roasted pellets were ground to pass a screen aperture of 75 microns for subsequent leaching.
• Ground roasted pellets were caustic leached under reflux conditions for 6 hours in a 10% NaOH solution at 6.7% solids density. Solid/liquid separation was effected by filtration, and the caustic leached products were washed and dried in preparation for subsequent acid leaching.
• Example 2 The same pellet formulations as indicated in Example 2 were made up in 350 kg batches in an agglomeration plant and roasted at 30 kg/hr feed rate with 15% brown coal char addition to a final temperature of 1000° C. in a small (0.5 m diameter) rotary kiln. Residence time above 900° C. was approximately 10 minutes. There were no problems with accretions or bed fusion, and after separation from residual char the products had exactly the same properties as the roasted products of Example 2.
• a commercial titania slag product having the composition indicated in Table 4 was processed as for the processing conditions indicated in Example 2, but with 2 wt % anhydrous borax addition in place of the other additives.
• the caustic leach was conducted at 165° C. under pressure, and a pressure leach with 20% sulphuric acid conducted at 135° C. was used in place of the hydrochloric acid leach.
• the final residue was calcined at 900° C. for one hour.
• the products of this treatment are indicated in Table 4.

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• 1993
  • 1993-08-12 JP JP6505674A patent/JPH08500393A/ja not_active Withdrawn
  • 1993-08-12 EP EP93917451A patent/EP0658214A4/de not_active Ceased
  • 1993-08-12 WO PCT/AU1993/000414 patent/WO1994004709A1/en not_active Application Discontinuation
  • 1993-08-13 MY MYPI93001605A patent/MY109520A/en unknown
  • 1993-08-13 IN IN462CA1993 patent/IN190922B/en unknown
  • 1993-08-14 CN CN93116218A patent/CN1043154C/zh not_active Expired - Fee Related
• 2001
  • 2001-04-26 US US09/819,095 patent/US20020104406A1/en not_active Abandoned
• 2003
  • 2003-01-16 US US10/345,286 patent/US20030129113A1/en not_active Abandoned

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