WO1999029626A1 - Improvements relating to the bayer process - Google Patents
Improvements relating to the bayer process Download PDFInfo
- Publication number
- WO1999029626A1 WO1999029626A1 PCT/US1998/026206 US9826206W WO9929626A1 WO 1999029626 A1 WO1999029626 A1 WO 1999029626A1 US 9826206 W US9826206 W US 9826206W WO 9929626 A1 WO9929626 A1 WO 9929626A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- liquor
- polysaccharide
- ppm
- dextran
- settler
- Prior art date
Links
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
- 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
- C01F7/0646—Separation of the insoluble residue, e.g. of red mud
- C01F7/0653—Separation of the insoluble residue, e.g. of red mud characterised by the flocculant added to the slurry
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
- C02F5/08—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents
- C02F5/10—Treatment of water with complexing chemicals or other solubilising agents for softening, scale prevention or scale removal, e.g. adding sequestering agents using organic substances
Definitions
- This invention relates to improvements to the Bayer process, in particular to a reduction of scale in the settler tank.
- alumina is refined from bauxite ores.
- the process comprises digesting the ore in a caustic solution to extract alumina, clarifying the liquor to remove caustic insoluble red mud material and precipitating alumina crystals as its trihydrate from the clarified liquor.
- Clarifying the liquor involves separating the solid particles from the liquor by settling and if necessary, filtration.
- the liquor is fed to a mud settler, or primary settler/thickener where it is treated with a flocculant, and as the mud settles, clarified sodium aluminate solution overflows the top of the settling tank where it is passed to subsequent process steps.
- the settled solids of the primary settler red mud
- the liquor entering the primary settler is highly reactive
- the present invention consists in a method for reducing scale in the Bayer process comprising:
- the polysaccharide used is dextran.
- a high molecular weight dextran having a molecular weight in excess of 500,000 is used although low density dextrans typically having a molecular weight of from 60,000 to 90,000 or 150,000 to 200,000 can also be used.
- Other polysaccharides can also be used.
- Combinations of dextran and starch are expected to be effective and may be more cost effective than the use of dextran alone .
- the polysaccharide is used in amounts less than 10 ppm, more preferably 0.5 ppm to 5 ppm, most preferably 1 to 2.5 ppm.
- the applicants have surprisingly found that even such a low amount of dextran is sufficient to minimize scale. It is thought that higher quantities of dextran are required when it is desired to suppress hydrate precipitation (of the order of 100-150 ppm) .
- the applicant believes that although lower concentrations are used in the inventive process, once the polysaccharide is attached to the red mud its local concentration is much higher than the bulk liquor concentration and thus may inhibit hydrate precipitation on the flocculated solids (i.e. seed poisoning as opposed to liquor stabilization) .
- the process may also comprise feeding the separated caustic insoluble materials to at least one washer and adding polysaccharide to the washer feed to minimize scaling in the washer.
- Figure 1 is a graph of the liquid level in a settler tank over time.
- a number of settler tanks hereinafter referred to as Fll, F12, F13 , F21, F22, F23, F24, F31, F32 and F33, were introduced over the course of several months into a Bayer process operation to receive digested aluminous ore.
- Settler tanks Fll, F13 and F32 were each provided with launder scapers to physically descale the tank online during the Bayer process operation.
- F32 was also provided with a weir descaler.
- Settler tanks F12 , F22 and F31 were initially used unmodified following which dextran at various concentrations was added to each of the tanks. In this regard, dextran was added to settler tank F12 on 17 October at an initial concentration of 1.3 ppm.
- Dextran was added to settler tank F22 on 16 August at an initial concentration of 2.6 ppm, the concentration being dropped over time to a minimum value of 1.3 ppm just prior to 9 October when it was increased back to 2.6 ppm.
- Dextran was added to settler tank F31 on 23 October at an initial concentration of 1.3 ppm.
- F21 was initially used unmodified and taken off-line for mechanical descaling following which the tank was brought back on-line on 19 August with addition of dextran added at various concentrations.
- the dextran was initially added to tank F21 at a concentration of 0.7 ppm the concentration being dropped over time to a minimum value of 0.5 ppm just prior to 9 October when it was increased to 1.0 ppm.
- Settler tanks F23 and F24 were used unmodified although some on-line descaling of F24 was performed during August . Both tanks were then taken off for mechanical descaling. Both these tanks are yet to be brought back on-line. Finally settler tank F33 was used unmodified and taken off-line for mechanical descaling following which the tank was brought back online and again used unmodified with addition of a high molecular weight, highly anionic sodium polyacrylate flocculant .
- the dextran was used as an aqueous solution.
- Coupons from each of the tanks were also analyzed. Coupons from tanks F21, F22 and F32 were relatively clean with a fine coating of mud-like scale and a small pile of fine settled scale on the horizontal surface. The remaining coupons showed more typical coarse settled scale and a more significant build-up of scale on the vertical surfaces. The coupon from F33 was heavily scaled.
- A/TC ratio drop results for each tank were obtained.
- A/TC is the alumina/total caustic ratio and is calculated from g/1 Al 2 0 3 divided by g/1 NaOH expressed as Na 2 C0 3 .
- the results from tanks F21 and F22 were no less than the results from the other vessels indicating that dextran is not acting to stabilize the liquor.
- 0% in the graph refers to a full tank without the presence of any scale.
- 100% refers to an overfull tank having liquor up to the roof of the launder. This condition requires the tank to be taken off-line and descaled.
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Environmental & Geological Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98963023A EP1044164A4 (en) | 1997-12-11 | 1998-12-10 | Improvements relating to the bayer process |
AU18135/99A AU1813599A (en) | 1997-12-11 | 1998-12-10 | Improvements relating to the bayer process |
BR9813467-1A BR9813467A (en) | 1997-12-11 | 1998-12-10 | Process to reduce fouling in the bayer process |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AUPP0849A AUPP084997A0 (en) | 1997-12-11 | 1997-12-11 | Improvements relating to the bayer process |
AUPP0849 | 1997-12-11 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999029626A1 true WO1999029626A1 (en) | 1999-06-17 |
Family
ID=3805134
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/026206 WO1999029626A1 (en) | 1997-12-11 | 1998-12-10 | Improvements relating to the bayer process |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1044164A4 (en) |
AU (2) | AUPP084997A0 (en) |
BR (1) | BR9813467A (en) |
WO (1) | WO1999029626A1 (en) |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10009369A1 (en) * | 2000-02-29 | 2001-08-30 | Vaw Ver Aluminium Werke Ag | Production of aluminum hydroxide gel, used e.g. as mordant, filler and pigment or in antihidrotic, toothpaste, paper, ceramics or abrasive, involves precipitation from diluted alkaline aluminate liquor, filtration, washing and drying |
EP1477811A1 (en) * | 2002-02-19 | 2004-11-17 | Kyowa Medex Co., Ltd. | Inhibitor of the adhesion of metal oxide-containing material to waste liquor line of automatic analyzer |
WO2012031316A1 (en) * | 2010-09-06 | 2012-03-15 | Alcoa Of Australia Limited | Method of increasing the stability of a bayer process liquor |
US9102995B2 (en) | 2010-08-09 | 2015-08-11 | Nalco Company | Cross-linked ethylsulfonated dihydroxypropyl cellulose |
US9199855B2 (en) | 2010-08-09 | 2015-12-01 | Nalco Company | Chemical treatment to improve red mud separation and washing in the bayer process |
US9284625B2 (en) | 2007-11-20 | 2016-03-15 | Nalco Company | Use of polyols as scale control reagents in the mining processes |
US9416490B2 (en) | 2010-03-10 | 2016-08-16 | Nalco Company | Cross-linked glycerol based polymers as digestion aids for improving wood pulping processes |
US10427950B2 (en) | 2015-12-04 | 2019-10-01 | Ecolab Usa Inc. | Recovery of mining processing product using boronic acid-containing polymers |
US10508042B2 (en) * | 2013-12-20 | 2019-12-17 | Rio Tinto Alcan International Limited | Process and installation for producing alumina trihydrate by alkaline digestion of bauxite ore |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2280998A (en) * | 1940-04-13 | 1942-04-28 | Aluminum Co Of America | Alumina recovery process |
US2930677A (en) * | 1955-01-31 | 1960-03-29 | Kaiser Aluminium Chem Corp | Method of handling liquors containing scale forming compounds |
US2935377A (en) * | 1957-08-23 | 1960-05-03 | Kaiser Aluminium Chem Corp | Starch-borax settling aid and process of using |
US3127239A (en) * | 1964-03-31 | Method of separation | ||
US3142637A (en) * | 1961-01-31 | 1964-07-28 | Reynolds Metals Co | Flocculating agent and process for digested bauxite slurries |
US3397953A (en) * | 1965-03-04 | 1968-08-20 | Atlas Chem Ind | Flocculating agent |
US3681012A (en) * | 1969-06-17 | 1972-08-01 | Nalco Chemical Co | Process for making alumina |
US3966874A (en) * | 1975-05-14 | 1976-06-29 | Reynolds Metals Company | Extraction of alumina from bauxite ores |
US5008089A (en) * | 1988-10-14 | 1991-04-16 | Allied Colloids Limited | Recovery of alumina from bauxite |
US5217620A (en) * | 1992-11-23 | 1993-06-08 | Nalco Chemical Company | Clarification aid for the Bayer process |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3085853A (en) * | 1958-12-23 | 1963-04-16 | Dow Chemical Co | Method of employing dextrans |
JPS5976598A (en) * | 1982-10-25 | 1984-05-01 | Mitsubishi Gas Chem Co Inc | Scale inhibiting agent |
GB8907995D0 (en) * | 1989-04-10 | 1989-05-24 | Allied Colloids Ltd | Recovery of alumina trihydrate in the bayer process |
DE69125659T2 (en) * | 1990-06-25 | 1997-07-31 | Nalco Australia | Modification of crystal growth |
US5091159A (en) * | 1991-06-10 | 1992-02-25 | Nalco Chemical Company | Use of dextran as a filtration aid for thickener overflow filtration in Kelly filters in the Bayer process |
-
1997
- 1997-12-11 AU AUPP0849A patent/AUPP084997A0/en not_active Abandoned
-
1998
- 1998-12-10 AU AU18135/99A patent/AU1813599A/en not_active Abandoned
- 1998-12-10 WO PCT/US1998/026206 patent/WO1999029626A1/en not_active Application Discontinuation
- 1998-12-10 EP EP98963023A patent/EP1044164A4/en not_active Withdrawn
- 1998-12-10 BR BR9813467-1A patent/BR9813467A/en not_active Application Discontinuation
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3127239A (en) * | 1964-03-31 | Method of separation | ||
US2280998A (en) * | 1940-04-13 | 1942-04-28 | Aluminum Co Of America | Alumina recovery process |
US2930677A (en) * | 1955-01-31 | 1960-03-29 | Kaiser Aluminium Chem Corp | Method of handling liquors containing scale forming compounds |
US2935377A (en) * | 1957-08-23 | 1960-05-03 | Kaiser Aluminium Chem Corp | Starch-borax settling aid and process of using |
US3142637A (en) * | 1961-01-31 | 1964-07-28 | Reynolds Metals Co | Flocculating agent and process for digested bauxite slurries |
US3397953A (en) * | 1965-03-04 | 1968-08-20 | Atlas Chem Ind | Flocculating agent |
US3575868A (en) * | 1965-03-04 | 1971-04-20 | Atlas Chem Ind | Flocculating agent comprising starch and polyacrylic acid |
US3681012A (en) * | 1969-06-17 | 1972-08-01 | Nalco Chemical Co | Process for making alumina |
US3966874A (en) * | 1975-05-14 | 1976-06-29 | Reynolds Metals Company | Extraction of alumina from bauxite ores |
US5008089A (en) * | 1988-10-14 | 1991-04-16 | Allied Colloids Limited | Recovery of alumina from bauxite |
US5217620A (en) * | 1992-11-23 | 1993-06-08 | Nalco Chemical Company | Clarification aid for the Bayer process |
Non-Patent Citations (1)
Title |
---|
See also references of EP1044164A4 * |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10009369A1 (en) * | 2000-02-29 | 2001-08-30 | Vaw Ver Aluminium Werke Ag | Production of aluminum hydroxide gel, used e.g. as mordant, filler and pigment or in antihidrotic, toothpaste, paper, ceramics or abrasive, involves precipitation from diluted alkaline aluminate liquor, filtration, washing and drying |
EP1477811A1 (en) * | 2002-02-19 | 2004-11-17 | Kyowa Medex Co., Ltd. | Inhibitor of the adhesion of metal oxide-containing material to waste liquor line of automatic analyzer |
EP1477811A4 (en) * | 2002-02-19 | 2005-04-27 | Kyowa Medex Co Ltd | Inhibitor of the adhesion of metal oxide-containing material to waste liquor line of automatic analyzer |
US9284625B2 (en) | 2007-11-20 | 2016-03-15 | Nalco Company | Use of polyols as scale control reagents in the mining processes |
US10112843B2 (en) | 2007-11-20 | 2018-10-30 | Ecolab Usa Inc. | Use of polyols as scale control reagents in the mining processes |
US9416490B2 (en) | 2010-03-10 | 2016-08-16 | Nalco Company | Cross-linked glycerol based polymers as digestion aids for improving wood pulping processes |
US9102995B2 (en) | 2010-08-09 | 2015-08-11 | Nalco Company | Cross-linked ethylsulfonated dihydroxypropyl cellulose |
US9199855B2 (en) | 2010-08-09 | 2015-12-01 | Nalco Company | Chemical treatment to improve red mud separation and washing in the bayer process |
WO2012031316A1 (en) * | 2010-09-06 | 2012-03-15 | Alcoa Of Australia Limited | Method of increasing the stability of a bayer process liquor |
US9187337B2 (en) | 2010-09-06 | 2015-11-17 | Alcoa Of Australia Limited | Method of increasing the stability of a Bayer process liquor |
AU2011301134B2 (en) * | 2010-09-06 | 2015-05-07 | Alcoa Of Australia Limited | Method of increasing the stability of a bayer process liquor |
US10508042B2 (en) * | 2013-12-20 | 2019-12-17 | Rio Tinto Alcan International Limited | Process and installation for producing alumina trihydrate by alkaline digestion of bauxite ore |
US10427950B2 (en) | 2015-12-04 | 2019-10-01 | Ecolab Usa Inc. | Recovery of mining processing product using boronic acid-containing polymers |
US11208332B2 (en) | 2015-12-04 | 2021-12-28 | Ecolab Usa Inc. | Recovery of mining processing product using boronic acid-containing polymers |
Also Published As
Publication number | Publication date |
---|---|
EP1044164A4 (en) | 2002-09-04 |
AU1813599A (en) | 1999-06-28 |
BR9813467A (en) | 2000-10-10 |
AUPP084997A0 (en) | 1998-01-08 |
EP1044164A1 (en) | 2000-10-18 |
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