WO2000010919A1 - Feed processing for improved alumina process performance - Google Patents
Feed processing for improved alumina process performance Download PDFInfo
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- WO2000010919A1 WO2000010919A1 PCT/AU1999/000663 AU9900663W WO0010919A1 WO 2000010919 A1 WO2000010919 A1 WO 2000010919A1 AU 9900663 W AU9900663 W AU 9900663W WO 0010919 A1 WO0010919 A1 WO 0010919A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- alumina
- feedstock
- treatment process
- treatment
- process defined
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Classifications
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- 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
- C22B21/00—Obtaining aluminium
- C22B21/0007—Preliminary treatment of ores or scrap or any other metal source
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/0613—Pretreatment of the minerals, e.g. grinding
-
- 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
Definitions
- This invention relates to the improvement of the mineralogical and chemical composition of naturally occurring and synthetic alumina process feedstocks.
- the invention is particularly suited to the enhancement of boehmitic bauxites used in the production of alumina and alumina chemicals, especially by the Bayer process.
- Embodiments of the present invention have the common feature of heating of the alumina process feedstock to bring about thermal dehydration and removal of organic carbon or conversion of organic carbon to a form which is not extractable in the aqueous phase digestion of the alumina process feedstock. Additional steps may be employed as will be described below.
- the dominant technology for the extraction of refined alumina from alumina process feedstocks is the Bayer process.
- alumina is extracted from alumina process feedstock (most frequently in the form of bauxite) by contacting the milled alumina process feedstock with hot caustic solution, generally under pressure, to dissolve alumina therefrom.
- the alumina process feedstock contains mainly gibbsite (a mineral form of alumina trihydrate)
- extraction of alumina from the bauxite may be conducted using a caustic solution at a temperature generally in the range 100 to 175C.
- the alumina process feedstock contains mainly boehmite, or diaspore (mineral forms of alumina monohydrate) higher temperatures, in the order of 200 to 300C are generally required.
- the higher temperature digestion is required in these cases because the monohydrate forms act to cause instability of caustic solutions containing the high levels of dissolved alumina desired for subsequent processing unless there is a high degree of elimination of these forms by digestion at temperatures where such liquors will be stable.
- High temperature digestion comes with significant equipment cost disadvantages, in a much larger liquor heating and flashing system (e.g. 11 stages compared with 3) and in more expensive materials and specifications for construction.
- a double digestion process in which residues from a lower temperature first stage digest are further digested in a higher temperature second stage digest, may be used.
- the digestion solid residue/pregnant caustic liquor mixture is brought back to atmospheric pressure by flashing to boil off water.
- the solid residue (usually referred to as red mud) is separated from the pregnant, caustic aluminate bearing liquor, usually by a combination of settling or filtration and washing, with both pregnant liquor and wash liquor clarified through pressure filters.
- the clarified combined liquor is fed to a precipitation circuit where it is cooled and seeded with solid particles of alumina trihydrate to induce precipitation of solid alumina trihydrate from the liquor.
- the resulting precipitation slurry is separated into a spent liquor stream and solids streams graded by particle size, by settling, cycloning or filtration, or combination of these processes.
- Coarse solids represent product, and are washed and transferred to a calcination stage where they are calcined to produce alumina. Intermediate and fine solids are separately returned to the precipitation circuit, frequently after at least crude deliquoring, e.g. in cyclones or filters, for agglomeration and to provide seed.
- the fine seed is normally washed prior to recycle to precipitation, either to remove solid phase oxalate precipitated with the alumina (which would interfere with the incorporation of the fine material into composite coarse particles in the precipitation process), or to remove organic compounds which would otherwise render the seed less active.
- the spent liquor is returned to the digestion step, normally after some reconcentration by evaporation, where it is contacted with further milled alumina process feedstock.
- Alumina process feedstocks particularly bauxites, include a range of impurities in addition to the hydrated forms of alumina.
- the main impurities are compounds of iron, titania and silica, which, while having various deleterious effects in the Bayer process, including on consumables such as flocculants, lime and caustic soda, and on scale formation and product quality, deport predominantly to the solid mud residue.
- extractable organic carbon (0.02% to 0.35%) is an impurity of major significance.
- Organic compounds, carbonates and oxalates derived from organic carbon in the feedstock have the capacity to accumulate in the circulating liquors, sequestering caustic soda which could otherwise have delivered alumina from digestion to precipitation, and therefore severely impacting on the productivity of the process.
- Oxalate derived from organic carbon is relatively insoluble, and can precipitate as sodium oxalate with the alumina trihydrate, interfering with product size, morphology and chemistry, and reducing resistance to particle attrition. Because these effects lead to the necessity to ensure that oxalate is not precipitated in the same precipitation tanks in which fine alumina is to be cemented into composite particles by the early portion of the precipitating alumina hydrate, and because oxalate stability above its solubility is a strong inverse function of liquor strength, the caustic strength available for carrying alumina is also limited in most alumina refineries by the input of oxalate precursors and oxalate generated by oxidation of other organics .
- organics in alumina process feeds are in large measure responsible for establishing the limits to productivity in the Bayer process, by setting the maximum level of soda in liquor, determining the extent to which this soda is sequestered from its useful purpose of delivering alumina, and acting as poisons for the precipitation process.
- the digestion temperature is frequently limited by the pressures at which boilers can operate safely and effectively, which results in a greater limitation on liquor alumina concentration for high temperature digestion than for low temperature digestion, given the instability of high alumina concentration liquors in the presence of solid residues which still contain destabilising monohydrate alumina.
- digestion of monohydrate alumina bearing alumina process feeds is naturally less productive than digestion of alumina bearing feeds with little or no monohydrate alumina.
- some alumina processing plants inject alumina bearing feeds having little or no monohydrate alumina into the cooling digestion liquors in the flashing vessels at temperatures and for contact times for which monohydrate alumina in high temperature digestion residues will not quickly cause liquor decomposition. This process is known as sweetening.
- the process adds significantly to processing complexity, requiring a separate milling and slurrying system for the injected feed having the low content of monohydrate alumina. Since important reactions which result in silica in feedstock forming solid sodium aluminosilicates (and therefore deporting to residues) cannot be completed at the times and temperatures of liquor/solids contact for the injected feedstock the sweetening process also elevates the level of dissolved silica in digestion liquors, causing elevated levels of silica subsequently precipitated with the alumina hydrate, and scaling problems in evaporation, alumina process feedstock slurrying, and liquor and slurry heating.
- an aluminosilicate seeded desilication operation after hydrate precipitation may be added to the flowsheet.
- high temperature digestion results in conversion of a substantial proportion of any quartz in the alumina process feedstock to sodium aluminosilicate, which deports to the digestion residue along with sodium aluminosilicate formed from more reactive forms of silica. Quartz is not significantly digested in low temperature digestion.
- Alumina process feedstocks having high contents of monohydrate alumina will, for an equivalent quartz and total silica content, consume more caustic soda, requiring greater make up of this expensive chemical. Further, such feedstocks will normally therefore benefit from treatment for the removal of liberated quartz particles prior to supply to the alumina refining process, at a further cost and process complexity, and usually for considerable loss of mineral values .
- Another influence of high temperature digestion is the conversion of some iron in the alumina process feedstock to soluble and colloidal forms which are able to pass through the clarifying system and deport in large measure to the precipitated alumina hydrate.
- the iron content of alumina hydrate, along with the silica content, is an important determinant of the value of the calcined hydrate to aluminium smelter customers, as it affects the quality of high purity metal which can be made.
- pressurised industrial oxygen is injected into circulating high temperature digestion liquors (possibly as a side stream, but also possibly in the main stream) to have the effect of conversion of organic impurities to oxidised gaseous species, and dissolved sodium carbonate, simpler organic compounds, and sodium oxalate.
- This process is always coupled with side stream processes for the removal of products of pressure oxidation, such as by causticisation with lime for the removal of carbonate, and side stream "salting out evaporation" in which a side stream is evaporated essentially to a cake of sodium salts including aluminate, carbonate, oxalate and organic compounds. This cake is either disposed of, or subjected to thermal decomposition for recovery of sodium and alumina values .
- Oxalate removal from the circuit is also conducted on a side stream, either the fine seed wash liquors or a stream of solid oxalate made by crystallisation from an evaporated side stream of spent liquor.
- the oxalate is reacted with lime to produce a calcium oxalate precipitate which is disposed of with red mud or, in the case of solid oxalate, can be thermally decomposed, usually in a process for destruction of other organics contained in concentrated liquors .
- Removal of carbonate by reaction with lime is also conducted on a side stream, in this case the wash liquors from solid residue washing.
- Brown specifically requires temperatures to be maintained in the range 300C to 400C for 10 to 120 minutes.
- Rijkeboer demonstrates that even with a test for extraction which provides for an optimistic view of extraction in the Bayer process (since it commences with pure caustic soda liquors instead of simulated spent Bayer liquor) the conditions indicated by Brown result in loss of extraction in realistic thermal processing equipment through the conversion of trihydrate alumina in feed to monohydrate alumina in the form of boehmite.
- Rijkeboer recommends a final temperature range of 400 to 600C and a retained chemical water below that of Kobayashi 's limitation.
- This limitation is extreme from an industrial processing point of view, since most industrial fuels will, upon combustion to introduce sufficient heat for dehydration at the required temperature, produce water vapour levels in combustion gases in excess of 2 kPa. Therefore the only means of conducting the process would be by heat transfer via heating elements which are themselves heated either electrically or via the combustion of fuel. For industrial processes treating at least hundreds of thousands of tonnes (and most probably millions of tonnes) of feed per year the required heat transfer area (of the heating elements) will not result in an economically attractive outcome.
- the water vapour pressure associated with completion of dehydration of the feed will be higher than 2 kPa unless there is very high dilution with air or some other gas, which even should heating via heating elements be used would result in the generation of large quantities of hot gases from which heat recovery in preheating and drying the feed would not be practical. Consequently none of the thermal processes proposed in the prior art which would have the impact of removal of organic matter accompanied by thermal dehydration while not significantly affecting the extractability of alumina from alumina process feeds can be operated under industrially realistic conditions.
- the present inventors have now proposed a process which is effective in meeting the need which has been identified, but without any of the above deficiencies.
- the present invention provides a process for the treatment of alumina process feedstocks for the simultaneous enhancement of achievable alumina digestion per unit of spent liquor and reduction in extractable organic carbon, which process comprise the following steps:
- the present inventors have surprisingly found that by limiting the contact time between hot, water vapour bearing gases and the alumina process feedstock while observing the above temperature limitations the extractable portion of organic carbon can be very significantly reduced, monohydrate alumina can be largely extinguished and trihydrate alumina can be converted to a more readily extracted and soluble form.
- the contact time is less than five minutes.
- the contact time is less than one minute.
- the contact time is less than 10 seconds.
- the average particle size of the alumina process feedstock is relatively fine to ensure that particle shells are not overheated or otherwise affected by water vapour.
- the particle size distribution is narrow, so that very fine particles are not overheated or otherwise affected by water vapour while the thermal treatment of the cores of the coarser particles is completed.
- Overgrinding is to be avoided, as it is a cost for little return, given that alumina refining processes can usually process feedstocks which would predominantly pass a 1mm aperture, and the present process can work quite effectively for materials having this size specification. Materials having a coarser specification will normally need to be reground following the present process before feeding to the alumina refining process .
- the best degree of milling is that which will just suit the desired size specification for the alumina refining process, performed in such a manner that an excessive amount of fine material is not produced.
- the alumina process feed is milled so that it does not contain more than a few percent by weight, more preferably no more than 5 wt%, of particles retained on a 5mm aperture.
- the alumina process feed is milled so that it does not contain more than a few percent by weight, more preferably no more than 5 wt%, of particles retained on a
- the alumina process feed is milled so that it does not contain more than a few percent by weight, more preferably no more than 5 wt%, retained on a 1mm aperture.
- the alumina process feed fed to the present process does not contain more than about 30% by weight of material which would pass a 20 micron aperture.
- the alumina process feed fed to the present process does not contain more than about 20% by weight of material which would pass a 20 micron aperture.
- the alumina process feed fed to the present process does not contain more than about 10% by weight of material which would pass a 20 micron aperture.
- Milling can be conducted in any suitable device. For example it may be conducted wet or dry, in rod or ball mills, semi-autogenously, in rolls or pressure rolls crushers, in roller mills or in vibro-mills. While the desired control of particle size distribution will best be achieved by milling in closed circuit with a classifying device the need for this will depend on the fracture characteristics of the alumina process feed, i.e. the degree to which it has a tendency to be overground in open circuit milling.
- closed circuit milling will beneficially be carried out in an air swept device, such as a roller mill or a rod, ball or semi-autogenous air swept mill.
- an air swept device such as a roller mill or a rod, ball or semi-autogenous air swept mill.
- hot gases from the heating step can be used for drying and milled product transport purposes, with associated economies in equipment and energy costs.
- the heating/gas contacting step (a) can be carried out in any device which is suitable for the contacting of fine granular materials with combustion gases mixed with preheated air for short and well controlled contact times followed by gas solids separation.
- Stationary (bubbling and spouting) fluidised beds will suit the longer contact times within the suitable range, circulating fluidised beds will suit the intermediate contact times, and will assist in the control of residence time according to particle size by allowing pneumatic classification prior to circulation of the coarser solids for recontacting with fresh gases, and flash and cyclone contacting systems, including gas suspension calciners with cyclone preheaters, will suit the shorter contact times for finer and more narrowly distributed particle sizes.
- the final heating and gas contacting of solids within the critical temperature range can be preceded by one or more preheating steps which bring about some thermal dehydration, reducing the thermal load, water vapour pressure and the necessary contact time in the final heating and gas contacting step.
- These one or more preheating steps can optionally be conducted in any of the above devices by contact with the exit gases from the final gas contacting step or from a later stage of preheating.
- countercurrent heat exchange can be conducted, with advantages for process fuel consumption, and the alumina process feedstock can be carefully conditioned so that naturally occurring variations in its properties have less influence on the product of the process.
- contact time or water vapour pressure in these lower temperature heating steps although very long times at low temperatures can produce some monohydrate alumina (which will nevertheless still decompose in the final gas contacting step) .
- Product cooling can be conducted in any practical manner. It is not necessary to cool to ambient temperature, as some of the heat in the product can be used in heating of alumina refinery liquors, saving some energy.
- Direct cooling to a suitable temperature probably 100 to 200C
- air which is preheated for process use either as preheated combustion air, as a heat carrier from the final stage into preheating stages, or as directly added hot air into preheating or drying stages
- indirect cooling can be applied without any other necessary disadvantage, if desired, either with or without heat recovery from the cooling fluid.
- alumina process feeds it is also possible to divide alumina process feeds according to their suitability for introduction to the process at different points having different conditions. It is herein disclosed that of the decomposition products of trihydrate alumina and monohydrate alumina it is the decomposition product of trihydrate alumina in alumina processing feedstocks which has the greatest extractability, and whose extractability is the most sensitive to process conditions, including water vapour sensitivity and overheating sensitivity. Thus the most vulnerable component of a feed to loss of potential extractability is the trihydrate alumina in the finer fractions of the feed. Further, trihydrate alumina can be suitably decomposed under milder temperature and contact time conditions than monohydrate alumina, under which conditions its decomposition product is less vulnerable to loss of potential extractability.
- the temperature sensitive fractions can be introduced downstream in the hot gases from the introduction of the high temperature demanding (e.g. coarse monohydrate bearing) fractions, so that the temperature sensitive fractions are at no point exposed to the highest temperature conditions.
- the presently disclosed process forms part of the chain of processing of alumina process feedstocks which embraces mining through to finished alumina. Accordingly in another aspect the present invention provides a Bayer process which includes the presently disclosed process.
- the present invention provides a Bayer process which includes the presently disclosed process.
- the weight of solids in the fluidised bed was determined as 2.5 kg, for an average solids residence time in the fluidised bed of about 11 minutes.
- the fluidised bed was maintained at a temperature of 540C.
- the fluidising air was introduced at a rate sufficient to provide a superficial velocity across the bed diameter of 0.7 metres per second at the bed temperature.
- Test 2 Two such tests were performed, one (Test 2) in which water was deliberately injected into the base of the fluidised bed to produce a water vapour pressure in the fluidising gases of 18 kPa, the other (Test 1) in which the water vapour pressure consisted only of that naturally obtained by the decomposition of the bauxite and the moisture content of the fluidising air (totalling approximately 5 kPa) .
- a weighed sample of each of the products was introduced into a small pressure vessel with 100 mL of synthetic spent Bayer liquor (caustic strength 280 gpL, expressed as sodium carbonate, sodium carbonate strength 30 gpL, alumina concentration 112 gpL A1203) .
- Liquor analysis for organic carbon and oxalate formation related back to the bauxite, indicated organic carbon and oxalate formation from the treated bauxite which were below the detection limit of the method used for analysis.
- the comparative values for the original bauxite were 0.20% and 0.9kg per tonne of bauxite.
- the above extraction test is a sensitive test of the extractability of the alumina in the feed, since it is conducted at relatively low temperatures for an originally boehmitic (monohydrate alumina bearing) bauxite, and a high alumina concentration relative to caustic concentration is targeted. In such a test applied to the original bauxite the extraction on the same basis is less than 80% of the available alumina.
- the higher extractions for the treated samples were somewhat further enhanced by extension of the digestion to two hours, which is not the observed behaviour for digestion of monohydrate bearing alumina process feeds, for which initial liquor alumina concentrations are not sustained with increasing time, due to decomposition onto monohydrate seed crystals in the digestion residue. No trihydrate alumina, monohydrate alumina or other crystalline decomposition product of monohydrate or trihydrate alumina was detectable by X-ray diffraction in either the product of processing or the digestion residues.
- the contact time of the solids in this system was similar to the gas residence time, which itself depended on the average gas velocity.
- the Weipa bauxite which contains both monohydrate and trihydrate forms of alumina, was passed through this arrangement twice, once at lower temperatures for preliminary dehydration, as would occur in feed preheaters, and once at higher temperatures for completion of dehydration to produce the desired product. In each pass an average gas velocity of 8 metres per second was used. The gas/solids contact time for each pass was therefore 1 to 2 seconds.
- the temperature profile for each pass is recorded in Figure 1.
- the product of the first pass retained 10.5% LOI, while the product of the second pass retained 4.3% LOI .
- This final product was subjected to digestion testing in the same manner as that described in Example 1, for an extraction of available alumina of 88.7%. Extractable organic carbon in the products was at or below 0.01%, and the oxalate formation rate was approximately 0.045 kg per tonne of the original bauxite. No trihydrate alumina, monohydrate alumina or other crystalline decomposition product of monohydrate or trihydrate alumina was detectable by X-ray diffraction in either the product of processing or the di ⁇ estion residue.
- Example 2 The same beneficiated, milled and dried bauxite as was used in Example 2 was processed at 0.6 tonne per hour feed rate through a countercurrent gas contacting arrangement consisting of three flash preheating tubes, with gas/solids separation between stages by cyclones, followed by a flash calciner, also equipped with a cyclone for gas/solids separation.
- the gases from the flash calciner were conducted after gas/solids separation to the third flash preheating tube for mixing with solids from the second flash heating stage, and then, after further gas/solids separation to the second flash preheating tube for mixing with the solids from the first flash heating stage, and finally , following yet another step of gas/solids separation, to the first flash preheating tube for mixing with fresh feed.
- Solids from earlier stages were conducted by gravity feed from locking valves at the bottom of the cyclones to the next flash heating stage.
- the process was controlled to provide an average gas velocity in the flash calciner of 6 metres per second for an incoming gas temperature of 660C, a calciner exit gas temperature of 585C, and an average temperature of about 610C, and for a water vapour pressure in incoming gas of 20 kPa.
- the preheated material fed to the flash calciner contained 7.0% of chemically bound water, and was at a temperature of approximately 415C.
- the gas residence time in the flash calciner was calculated as less than 1 second.
- the product was not substantially different in properties from the products of calcination described in Example 2, having an extractability above 88%.
- the process conditions and product properties were maintained for more than 24 hours of continuous running (i.e. for about 150,000 flash calcination cycles).
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002340971A CA2340971A1 (en) | 1998-08-17 | 1999-08-17 | Feed processing for improved alumina process performance |
EA200100251A EA002531B1 (en) | 1998-08-17 | 1999-08-17 | Feed processing for improved alumina process performance |
US09/763,065 US6616902B1 (en) | 1998-08-01 | 1999-08-17 | Feed processing for improved alumina process performance |
AU54977/99A AU727363B2 (en) | 1998-08-17 | 1999-08-17 | Feed processing for improved alumina process performance |
JP2000566198A JP2002523326A (en) | 1998-08-17 | 1999-08-17 | Feed processing for improved alumina processing performance |
EP99941318A EP1109740A4 (en) | 1998-08-17 | 1999-08-17 | Feed processing for improved alumina process performance |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPP5314A AUPP531498A0 (en) | 1998-08-17 | 1998-08-17 | Feed processing for improved alumina process performance |
AUPP5314 | 1998-08-17 |
Publications (1)
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WO2000010919A1 true WO2000010919A1 (en) | 2000-03-02 |
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ID=3809546
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/AU1999/000663 WO2000010919A1 (en) | 1998-08-01 | 1999-08-17 | Feed processing for improved alumina process performance |
Country Status (10)
Country | Link |
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US (1) | US6616902B1 (en) |
EP (1) | EP1109740A4 (en) |
JP (1) | JP2002523326A (en) |
CN (1) | CN1198762C (en) |
AU (1) | AUPP531498A0 (en) |
CA (1) | CA2340971A1 (en) |
EA (1) | EA002531B1 (en) |
MY (1) | MY123315A (en) |
OA (1) | OA11776A (en) |
WO (1) | WO2000010919A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008034196A1 (en) * | 2006-09-22 | 2008-03-27 | Alcoa Of Australia Limited | Method of concentrating a bayer process liquor |
Families Citing this family (4)
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CN102161050B (en) * | 2011-04-11 | 2012-09-26 | 德清县宝德炉料有限公司 | Method for treating waste sliding plates to recycle by biological method |
CN102258988A (en) * | 2011-05-12 | 2011-11-30 | 湖北航特科技有限责任公司 | Pretreatment method for pseudoboehmite with big specific surface area |
BR112015022243B1 (en) * | 2013-03-13 | 2022-02-15 | Nalco Company | METHOD TO PRODUCE ALUMINA USING A BAYER PROCESS |
CN107074575B (en) * | 2014-09-12 | 2019-05-28 | 尤萨科有限责任公司 | The manufacturing method of aluminium chloride derivative |
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FR1330185A (en) * | 1962-05-04 | 1963-06-21 | Electro Chimie Soc D | Improvement in the treatment of bauxites trihydrate |
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JPS533359B2 (en) * | 1971-09-27 | 1978-02-06 | ||
US5141734A (en) * | 1983-11-07 | 1992-08-25 | Aluminum Company Of America | Steam producing process |
CA2002172A1 (en) * | 1988-12-01 | 1990-06-01 | Neil Brown | Method for bauxite treatment |
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1998
- 1998-08-17 AU AUPP5314A patent/AUPP531498A0/en not_active Abandoned
-
1999
- 1999-08-17 CA CA002340971A patent/CA2340971A1/en not_active Abandoned
- 1999-08-17 JP JP2000566198A patent/JP2002523326A/en active Pending
- 1999-08-17 WO PCT/AU1999/000663 patent/WO2000010919A1/en not_active Application Discontinuation
- 1999-08-17 EA EA200100251A patent/EA002531B1/en not_active IP Right Cessation
- 1999-08-17 CN CNB998105554A patent/CN1198762C/en not_active Expired - Fee Related
- 1999-08-17 OA OA1200100042A patent/OA11776A/en unknown
- 1999-08-17 US US09/763,065 patent/US6616902B1/en not_active Expired - Fee Related
- 1999-08-17 EP EP99941318A patent/EP1109740A4/en not_active Withdrawn
- 1999-08-17 MY MYPI99003531A patent/MY123315A/en unknown
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FR1106778A (en) * | 1954-06-10 | 1955-12-22 | Pechiney | Improvement in the preparation of activated alumina from hydrargillite |
US2915365A (en) * | 1954-06-28 | 1959-12-01 | Pechiney Prod Chimiques Sa | Method of preparing activated alumina from commercial alpha alumina trihydrate |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008034196A1 (en) * | 2006-09-22 | 2008-03-27 | Alcoa Of Australia Limited | Method of concentrating a bayer process liquor |
AU2007299598B2 (en) * | 2006-09-22 | 2010-11-18 | Alcoa Of Australia Limited | Method of concentrating a Bayer process liquor |
Also Published As
Publication number | Publication date |
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CA2340971A1 (en) | 2000-03-02 |
CN1198762C (en) | 2005-04-27 |
MY123315A (en) | 2006-05-31 |
OA11776A (en) | 2005-07-26 |
JP2002523326A (en) | 2002-07-30 |
EA200100251A1 (en) | 2001-08-27 |
EP1109740A4 (en) | 2006-06-28 |
CN1324328A (en) | 2001-11-28 |
EP1109740A1 (en) | 2001-06-27 |
US6616902B1 (en) | 2003-09-09 |
AUPP531498A0 (en) | 1998-09-10 |
EA002531B1 (en) | 2002-06-27 |
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