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EP1044164A1 - Perfectionnements se rapportant au procede bayer - Google Patents

Perfectionnements se rapportant au procede bayer

Info

Publication number
EP1044164A1
EP1044164A1 EP98963023A EP98963023A EP1044164A1 EP 1044164 A1 EP1044164 A1 EP 1044164A1 EP 98963023 A EP98963023 A EP 98963023A EP 98963023 A EP98963023 A EP 98963023A EP 1044164 A1 EP1044164 A1 EP 1044164A1
Authority
EP
European Patent Office
Prior art keywords
liquor
polysaccharide
ppm
dextran
settler
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.)
Withdrawn
Application number
EP98963023A
Other languages
German (de)
English (en)
Other versions
EP1044164A4 (fr
Inventor
John David Kildea
Grant William Doberer
John Christopher Meldrum
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ChampionX LLC
Original Assignee
Nalco Chemical Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nalco Chemical Co filed Critical Nalco Chemical Co
Publication of EP1044164A1 publication Critical patent/EP1044164A1/fr
Publication of EP1044164A4 publication Critical patent/EP1044164A4/fr
Withdrawn legal-status Critical Current

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)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Water Supply & Treatment (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Inorganic Chemistry (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)

Abstract

La présente invention concerne un procédé permettant de réduire l'entartrage dans le procédé bayer. Ce procédé consiste d'abord (a) à digérer un minerai aluminique dans une liqueur caustique pour en extraire les valeurs aluminiques. Le procédé consiste ensuite (b) à amener la liqueur dans un décanteur pour clarifier la liqueur par séparation des substances caustiques insolubles. Le procédé consiste alors (c) à précipiter en cristaux l'alumine dans la liqueur clarifiée. Le procédé consiste en outre à ajouter dans l'amenée du décanteur un polysaccharide à raison de moins de 50 ppm, proportion restant suffisante pour ramener à un minimum l'entartrage et à prolonger l'intervalle entre deux détartrages par comparaison à l'utilisation d'une amenée sans adjonction de polysaccharide. Le procédé de l'invention permet de prolonger sensiblement l'intervalle entre deux détartrages, parfois de plus de 100 %.
EP98963023A 1997-12-11 1998-12-10 Perfectionnements se rapportant au procede bayer Withdrawn EP1044164A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AUPP0849A AUPP084997A0 (en) 1997-12-11 1997-12-11 Improvements relating to the bayer process
AUPP084997 1997-12-11
PCT/US1998/026206 WO1999029626A1 (fr) 1997-12-11 1998-12-10 Perfectionnements se rapportant au procede bayer

Publications (2)

Publication Number Publication Date
EP1044164A1 true EP1044164A1 (fr) 2000-10-18
EP1044164A4 EP1044164A4 (fr) 2002-09-04

Family

ID=3805134

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98963023A Withdrawn EP1044164A4 (fr) 1997-12-11 1998-12-10 Perfectionnements se rapportant au procede bayer

Country Status (4)

Country Link
EP (1) EP1044164A4 (fr)
AU (2) AUPP084997A0 (fr)
BR (1) BR9813467A (fr)
WO (1) WO1999029626A1 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10009369A1 (de) * 2000-02-29 2001-08-30 Vaw Ver Aluminium Werke Ag Aluminiumhydroxidgel
TW200303987A (en) * 2002-02-19 2003-09-16 Kyowa Medex Co Ltd Adhesion inhibiting agent for preventing metal hydroxide-containing substance from adhering to the drain 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
US9416490B2 (en) 2010-03-10 2016-08-16 Nalco Company Cross-linked glycerol based polymers as digestion aids for improving wood pulping processes
US9199855B2 (en) 2010-08-09 2015-12-01 Nalco Company Chemical treatment to improve red mud separation and washing in the bayer process
US9102995B2 (en) 2010-08-09 2015-08-11 Nalco Company Cross-linked ethylsulfonated dihydroxypropyl cellulose
BR112013005398B1 (pt) * 2010-09-06 2021-05-04 Alcoa Of Australia Limited métodos para aumentar a estabilidade de um licor e para controlar a precipitação de compostos contendo alumínio de licores do processo bayer
EP2886178A1 (fr) * 2013-12-20 2015-06-24 Rio Tinto Alcan International Limited Procédé et installation de production de trihydrate d'alumine par digestion d'alcaline de minerai de bauxite
US10427950B2 (en) 2015-12-04 2019-10-01 Ecolab Usa Inc. Recovery of mining processing product using boronic acid-containing polymers

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3085853A (en) * 1958-12-23 1963-04-16 Dow Chemical Co Method of employing dextrans
US4561982A (en) * 1982-10-25 1985-12-31 Mitsubishi Gas Chemical Company, Inc. Scale inhibitor
EP0392779A1 (fr) * 1989-04-10 1990-10-17 Ciba Specialty Chemicals Water Treatments Limited Récupération d'hydroxyde d'aluminium dans le procédé Bayer
US5008089A (en) * 1988-10-14 1991-04-16 Allied Colloids Limited Recovery of alumina from bauxite
EP0465055A1 (fr) * 1990-06-25 1992-01-08 Nalco Australia Pty. Limited Modification de la croissance de cristaux
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
US5217620A (en) * 1992-11-23 1993-06-08 Nalco Chemical Company Clarification aid for the Bayer process

Family Cites Families (8)

* Cited by examiner, † Cited by third party
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
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

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3085853A (en) * 1958-12-23 1963-04-16 Dow Chemical Co Method of employing dextrans
US4561982A (en) * 1982-10-25 1985-12-31 Mitsubishi Gas Chemical Company, Inc. Scale inhibitor
US5008089A (en) * 1988-10-14 1991-04-16 Allied Colloids Limited Recovery of alumina from bauxite
EP0392779A1 (fr) * 1989-04-10 1990-10-17 Ciba Specialty Chemicals Water Treatments Limited Récupération d'hydroxyde d'aluminium dans le procédé Bayer
EP0465055A1 (fr) * 1990-06-25 1992-01-08 Nalco Australia Pty. Limited Modification de la croissance de cristaux
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
US5217620A (en) * 1992-11-23 1993-06-08 Nalco Chemical Company Clarification aid for the Bayer process

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO9929626A1 *

Also Published As

Publication number Publication date
AU1813599A (en) 1999-06-28
EP1044164A4 (fr) 2002-09-04
BR9813467A (pt) 2000-10-10
AUPP084997A0 (en) 1998-01-08
WO1999029626A1 (fr) 1999-06-17

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